The 2021 Arizona Diamondbacks season was their 23rd season in Major League Baseball and also 23rd season at Chase Field in Phoenix, Arizona as members of the National League West. They were managed by Torey Lovullo in his fifth season with the franchise.

The Diamondbacks suffered a massive losing skid over 45 games from the 29th game against the Marlins to the 73rd game against the Dodgers that saw them only win 5 games that plunged their record from a 15–13 start to a 20–53 record including a franchise record 17-game losing streak. On June 17, 2021, with a 10–3 loss to the Giants, the team broke a dubious record of most consecutive road losses in the modern era, with 23 (which would later reach 24, equaling the all-time record of the 1889 Louisville Colonels). The MLB record was previously held by the 1943 Philadelphia Athletics and the 1963 New York Mets. One day later, they set a franchise record with their fifteenth consecutive loss, home or away. That streak would end at 17.

On August 14, 2021, Tyler Gilbert threw the third no-hitter in Diamondbacks history. This was his first Major League start, and the second no-hitter thrown at Chase Field. The Diamondbacks finished the 2021 season in fifth place in the National League West, with a 52–110 record, one game shy of tying their franchise-worst 2004 season, 51–111.

Season standings National League West

National League Wild Card

Record vs. opponents

Regular season Game log

|- style="background:#fbb;" | 1 || April 1 || @ Padres || 7–8 || Pagán (1–0) || Young (0–1) || Melancon (1) || 8,773 || 0–1 || L1 |- style="background:#fbb;" | 2 || April 2 || @ Padres || 2–4 || Pagán (2–0) || Kelly (0–1) || Melancon (2) || 10,350 || 0–2 || L2 |- style="background:#fbb;" | 3 || April 3 || @ Padres || 0–7 || Musgrove (1–0) || C. Smith (0–1) || Weathers (1) || 10,350 || 0–3 || L3 |- style="background:#bfb;" | 4 || April 4 || @ Padres || 3–1 || Widener (1–0) || Paddack (0–1) || Devenski (1) || 10,350 || 1–3 || W1 |- style="background:#bfb;" | 5 || April 6 || @ Rockies || 10–8 || Peacock (1–0) || Bowden (0–1) || — || 10,240 || 2–3 || W2 |- style="background:#fbb;" | 6 || April 7 || @ Rockies || 0–8 || Senzatela (1–1) || Bumgarner (0–1) || — || 12,894 || 2–4 || L1 |- style="background:#fbb;" | 7 || April 8 || @ Rockies || 3–7 || Gray (1–0) || Kelly (0–2) || Bard (2) || 10,836 || 2–5 || L2 |- style="background:#fbb;" | 8 || April 9 || Reds || 5–6 || Pérez (1–0) || Young (0–2) || Garrett (2) || 19,385 || 2–6 || L3 |- style="background:#bfb;" | 9 || April 10 || Reds || 8–3 || R. Smith (1–0) || Hoffman (1–0) || — || 13,208 || 3–6 || W1 |- style="background:#bfb;" | 10 || April 11 || Reds || 7–0 || Weaver (1–0) || De León (0–1) || — || 10,981 || 4–6 || W2 |- style="background:#fbb;" | 11 || April 12 || Athletics || 5–9 || Bassitt (1–2) || Bumgarner (0–2) || — || 8,768 || 4–7 || L1 |- style="background:#fbb;" | 12 || April 13 || Athletics || 5–7 || Petit (3–0) || Swarzak (0–1) || Trivino (1) || 7,010 || 4–8 || L2 |- style="background:#bfb;" | 13 || April 15 || @ Nationals || 11–6 || Kelly (1–2) || Corbin (0–2) || — || 6,666 || 5–8 || W1 |- style="background:#fbb;" | 14 || April 16 || @ Nationals || 0–1 || Hand (1–0) || Young (0–3) || — || 8,056 || 5–9 || L1 |- style="background:#fbb;" | 15 || April 17 || @ Nationals || 2–6 || Fedde (1–1) || Weaver (1–1) || — || 8,305 || 5–10 || L2 |- style="background:#bfb;" | 16 || April 18 || @ Nationals || 5–2 || Bumgarner (1–2) || Espino (0–1) || Crichton (1) || 8,478 || 6–10 || W1 |- style="background:#bbb;" | — || April 20 || @ Reds || colspan=7 | Suspended (Rain, continuation date: April 21) |- style="background:#bfb;" | 17 || April 21 || @ Reds || 5–4 || Bukauskas (1–0) || Garrett (0–1) || Crichton (2) || 8,085 || 7–10 || W2 |- style="background:#bfb;" | 18 || April 21 || @ Reds || 8–5 || Clarke (1–0) || Pérez (1–2) || — || 8,025 || 8–10 || W3 |- style="background:#bfb;" | 19 || April 22 || @ Reds || 14–11 || C. Smith (1–1) || Sims (0–1) || — || 7,549 || 9–10 || W4 |- style="background:#fbb;" | 20 || April 23 || @ Braves || 4–5 || Ynoa (1–1) || Weaver (1–2) || Smith (4) || 19,258 || 9–11 || L1 |- style="background:#bbb;" | — || April 24 || @ Braves || colspan=7 | Postponed (Rain, makeup date: April 25) |- style="background:#bfb;" | 21 || April 25 || @ Braves || 5–0 || Gallen (1–0) || Wilson (1–1) || — || N/A || 10–11 || W1 |- style="background:#bfb;" | 22 || April 25 || @ Braves || 7–0 || Bumgarner (2–2) || Smyly (0–1) || — || 20,693 || 11–11 || W2 |- style="background:#bfb;" | 23 || April 27 || Padres || 5–1 || Kelly (2–2) || Paddack (1–3) || — || 10,486 || 12–11 || W3 |- style="background:#fbb;" | 24 || April 28 || Padres || 3–12 || Northcraft (1–0) || R. Smith (1–1) || — || 9,495 || 12–12 || L1 |- style="background:#bfb;" | 25 || April 29 || Rockies || 5–3 || C. Smith (2–1) || Stephenson (0–1) || Crichton (3) || 6,843 || 13–12 || W1 |- style="background:#bfb;" | 26 || April 30 || Rockies || 7–2 || Bumgarner (3–2) || Gray (3–2) || — || 13,184 || 14–12 || W2

|- style="background:#fbb;" | 27 || May 1 || Rockies || 6–14 || Gomber (2–3) || Gallen (1–1) || — || 15,734 || 14–13 || L1 |- style="background:#bfb;" | 28 || May 2 || Rockies || 8–4 || Devenski (1–0) || Bard (1–2) || — || 11,395 || 15–13 || W1 |- style="background:#fbb;" | 29 || May 4 || @ Marlins || 3–9 || Bleier (2–0) || Ginkel (0–1) || — || 3,893 || 15–14 || L1 |- style="background:#fbb;" | 30 || May 5 || @ Marlins || 0–8 || Holloway (1–0) || Weaver (1–3) || — || 3,573 || 15–15 || L2 |- style="background:#fbb;" | 31 || May 6 || @ Marlins || 1–3 || Floro (2–1) || Bukauskas (1–1) || García (5) || 4,049 || 15–16 || L3 |- style="background:#fbb;" | 32 || May 7 || @ Mets || 4–5 || Loup (1–0) || Crichton (0–1) || — || 7,662 || 15–17 || L4 |- style="background:#fbb;" | 33 || May 8 || @ Mets || 2–4 || Lucchesi (1–2) || Kelly (2–3) || May (1) || 7,908 || 15–18 || L5 |- style="background:#fbb;" | 34 || May 9 || @ Mets || 2–4 || deGrom (3–2) || R. Smith (1–2) || Díaz (5) || 7,880 || 15–19 || L6 |- style="background:#bfb;" | 35 || May 10 || Marlins || 5–2 || Weaver (2–3) || Holloway (1–1) || Crichton (4) || 6,307 || 16–19 || W1 |- style="background:#bfb;" | 36 || May 11 || Marlins || 11–3 || Bumgarner (4–2) || López (0–3) || — || 5,560 || 17–19 || W2 |- style="background:#fbb;" | 37 || May 12 || Marlins || 2–3 || Poteet (1–0) || Peacock (1–1) || García (6) || 5,714 || 17–20 || L1 |- style="background:#fbb;" | 38 || May 13 || Marlins || 1–5 || Rogers (5–2) || Kelly (2–4) || — || 5,967 || 17–21 || L2 |- style="background:#fbb;" | 39 || May 14 || Nationals || 2–17 || Scherzer (3–2) || R. Smith (1–3) || — || 11,907 || 17–22 || L3 |- style="background:#bfb;" | 40 || May 15 || Nationals || 11–4 || Young (1–3) || Ross (2–3) || — || 13,462 || 18–22 || W1 |- style="background:#fbb;" | 41 || May 16 || Nationals || 0–3 || Fedde (3–4) || Crichton (0–2) || Hand (4) || 11,619 || 18–23 || L1 |- style="background:#fbb;" | 42 || May 17 || @ Dodgers || 1–3 || Buehler (2–0) || Bumgarner (4–3) || Jansen (8) || 14,088 || 18–24 || L2 |- style="background:#fbb;" | 43 || May 18 || @ Dodgers || 1–9 || Urías (6–1) || Martin (0–1) || — || 15,313 || 18–25 || L3 |- style="background:#fbb;" | 44 || May 19 || @ Dodgers || 2–4 || Kelly (1–0) || Mantiply (0–1) || Jansen (9) || 15,586 || 18–26 || L4 |- style="background:#fbb;" | 45 || May 20 || @ Dodgers || 2–3 || González (1–0) || Kelly (2–5) || Jansen (10) || 16,105 || 18–27 || L5 |- style="background:#fbb;" | 46 || May 21 || @ Rockies || 1–7 || Márquez (3–4) || Frankoff (0–1) || — || 18,158 || 18–28 || L6 |- style="background:#fbb;" | 47 || May 22 || @ Rockies || 6–7 || Kinley (1–0) || Bumgarner (4–4) || Bard (5) || 20,183 || 18–29 || L7 |- style="background:#fbb;" | 48 || May 23 || @ Rockies || 3–4 || Bard (2–3) || Crichton (0–3) || — || 19,221 || 18–30 || L8 |- style="background:#fbb;" | 49 || May 25 || Giants || 0–8 || Gausman (5–0) || Martin (0–2) || — || 10,311 || 18–31 || L9 |- style="background:#fbb;" | 50 || May 26 || Giants || 4–5 || Tropeano (1–0) || Young (1–4) || Rogers (6) || 8,597 || 18–32 || L10 |- style="background:#fbb;" | 51 || May 27 || Cardinals || 4–5 || Reyes (3–1) || Crichton (0–4) || Ponce de Leon (1) || 8,951 || 18–33 || L11 |- style="background:#fbb;" | 52 || May 28 || Cardinals || 6–8 || Woodford (1–0) || Bumgarner (4–5) || Ponce de Leon (2) || 11,581 || 18–34 || L12 |- style="background:#fbb;" | 53 || May 29 || Cardinals || 4–7 || Wainwright (3–4) || Frankoff (0–2) || Reyes (15) || 17,834 || 18–35 || L13 |- style="background:#bfb;" | 54 || May 30 || Cardinals || 9–2 || Peacock (2–1) || Kim (1–3) || R. Smith (1) || 16,681 || 19–35 || W1 |- style="background:#fbb;" | 55 || May 31 || Mets || 2–6 || deGrom (4–2) || Kelly (2–6) || — || 11,309 || 19–36 || L1

|- style="background:#bfb;" | 56 || June 1 || Mets || 6–5 || Young (2–4) || May (2–2) || — || 9,590 || 20–36 || W1 |- style="background:#fbb;" | 57 || June 2 || Mets || 6–7 || Castro (2–1) || Soria (0–1) || Díaz (10) || 9,810 || 20–37 || L1 |- style="background:#fbb;" | 58 || June 3 || @ Brewers || 4–7 || Suter (6–3) || Duplantier (0–1) || Hader (13) || 12,392 || 20–38 || L2 |- style="background:#fbb;" | 59 || June 4 || @ Brewers || 1–5 || Peralta (6–1) || Peacock (2–2) || — || 15,261 || 20–39 || L3 |- style="background:#fbb;" | 60 || June 5 || @ Brewers || 5–7 || Williams (2–0) || Soria (0–2) || Hader (14) || 20,073 || 20–40 || L4 |- style="background:#fbb;" | 61 || June 6 || @ Brewers || 0–2 || Burnes (3–4) || C. Smith (2–2) || Boxberger (2) || 20,117 || 20–41 || L5 |- style="background:#fbb;" | 62 || June 8 || @ Athletics || 2–5 || Bassitt (6–2) || Duplantier (0–2) || Trivino (9) || 3,695 || 20–42 || L6 |- style="background:#fbb;" | 63 || June 9 || @ Athletics || 0–4 || Manaea (5–2) || Peacock (2–3) || — || 4,090 || 20–43 || L7 |- style="background:#fbb;" | 64 || June 11 || Angels || 5–6 || Iglesias (4–2) || Buchter (0–1) || Claudio (1) || 18,458 || 20–44 || L8 |- style="background:#fbb;" | 65 || June 12 || Angels || 7–8 || Claudio (1–1) || Soria (0–3) || Iglesias (11) || 13,863 || 20–45 || L9 |- style="background:#fbb;" | 66 || June 13 || Angels || 3–10 || Sandoval (1–2) || Duplantier (0–3) || — || 12,768 || 20–46 || L10 |- style="background:#fbb;" | 67 || June 14 || @ Giants || 2–5 || Wood (6–3) || Peacock (2–4) || McGee (13) || 9,906 || 20–47 || L11 |- style="background:#fbb;" | 68 || June 15 || @ Giants || 8–9 || Sherfy (1–0) || Castellanos (0–1) || Rogers (9) || 9,867 || 20–48 || L12 |- style="background:#fbb;" | 69 || June 16 || @ Giants || 7–13 || DeSclafani (7–2) || Kelly (2–7) || — || 11,004 || 20–49 || L13 |- style="background:#fbb;" | 70 || June 17 || @ Giants || 3–10 || Gausman (8–1) || Gallen (1–2) || — || 13,144 || 20–50 || L14 |- style="background:#fbb;" | 71 || June 18 || Dodgers || 0–3 || Bauer (7–5) || Mantiply (0–2) || Jansen (17) || 25,356 || 20–51 || L15 |- style="background:#fbb;" | 72 || June 19 || Dodgers || 3–9 || Buehler (7–0) || Peacock (2–5) || — || 29,904 || 20–52 || L16 |- style="background:#fbb;" | 73 || June 20 || Dodgers || 8–9 || Cleavinger (2–3) || Young (2–5) || Jansen (18) || 31,661 || 20–53 || L17 |- style="background:#bfb;" | 74 || June 21 || Brewers || 5–1 || Kelly (3–7) || Anderson (2–5) || — || 9,804 || 21–53 || W1 |- style="background:#fbb;" | 75 || June 22 || Brewers || 0–5 || Peralta (7–2) || Gallen (1–3) || — || 9,358 || 21–54 || L1 |- style="background:#fbb;" | 76 || June 23 || Brewers || 2–3 || Woodruff (6–3) || C. Smith (2–3) || Hader (19) || 8,676 || 21–55 || L2 |- style="background:#fbb;" | 77 || June 25 || @ Padres || 5–11 || Ramirez (1–1) || Martin (0–3) || — || 32,583 || 21–56 || L3 |- style="background:#bfb;" | 78 || June 26 || @ Padres || 10–1 || Kelly (4–7) || Lamet (2–3) || — || 40,557 || 22–56 || W1 |- style="background:#fbb;" | 79 || June 27 || @ Padres || 4–5 || Hill (5–3) || Peacock (2–6) || Melancon (24) || 34,905 || 22–57 || L1