Defending champion Monica Seles defeated Gabriela Sabatini in the final, 6–3, 7–5 to win the women's singles tennis title at the 1991 Miami Open.
Seeds All seeds received a bye into the second round.
Steffi Graf (semifinals) Monica Seles (champion) Gabriela Sabatini (final) Mary Joe Fernández (semifinals) Zina Garrison-Jackson (quarterfinals) Jennifer Capriati (quarterfinals) Manuela Maleeva-Fragniere (quarterfinals) Natasha Zvereva (second round) Barbara Paulus (fourth round) Nathalie Tauziat (fourth round) Helen Kelesi (second round) Amy Frazier (third round) Laura Gildemeister (third round) Rosalyn Fairbank-Nideffer (second round) Naoko Sawamatsu (third round) Raffaella Reggi (fourth round) Lori McNeil (third round) Manon Bollegraf (second round) Catarina Lindqvist (second round) Susan Sloane (second round) Gretchen Magers (third round) Regina Rajchrtová (fourth round) Meredith McGrath (third round) Carrie Cunningham (second round) Julie Halard (second round) Ann Grossman (third round) Marianne Werdel (fourth round) Cathy Caverzasio (second round) Wiltrud Probst (second round) Eva Švíglerová (third round) Stephanie Rehe (second round) Elizabeth Smylie (third round)
Draw
Finals
Top half
Section 1
Section 2
Section 3
Section 4
Bottom half
Section 5
Section 6
Section 7
Section 8
Qualifying
Seeds
Camille Benjamin (Promoted to Main Draw) Renata Baranski (second round) Bettina Fulco (second round) Nathalie Guerrée (first round) Clare Wood (qualified) Eva Pfaff (second round) Maïder Laval (qualifying competition) Michelle Jaggard (second round) Sandra Wasserman (qualified) Hu Na (first round) Cláudia Chabalgoity (second round) Claudine Toleafoa (qualified) Noëlle van Lottum (first round) Pascale Etchemendy (first round) Andrea Vieira (first round) Julie Richardson (qualifying competition)
Qualifiers
Rene Simpson-Alter Stacey Schefflin Nathalie Housset Claudine Toleafoa Clare Wood Yael Segal Miriam Oremans Petra Thorén
Draw
First qualifier
Second qualifier
Third qualifier
Fourth qualifier
Fifth qualifier
Sixth qualifier
Seventh qualifier
Eighth qualifier
References Main and Qualifying Draws Official results archive (WTA)