Diaby is a surname, and may refer to:

• Abdoulay Diaby (born 1991), Malian football player
• Abou Diaby (born 1986), French football midfielder
• Aboubakar Diaby Ouattara, Ivorian diplomat
• Alassane Diaby (born 1995), French-born Malian football player
• Karamba Diaby (born 1961), Senegalese-born German chemist and politician
• Karim Coulibaly Diaby (born 1989), French-Ivorian football striker
• Lassina Diaby (born 1992), Ivorian footballer
• Mohamed Diaby (born 1990), Ivorian football midfielder
• Moussa Diaby (born 1999), French football forward
• Oumar Diaby (born 1990), French football forward
• Oumarou Diaby (born 1987), French football midfielder
• Sékana Diaby (born 1968), former Ivorian football defender
• Souleymane Diaby (born 1987), Ivorian football striker of Guinean descent
• YaYa Diaby (born 1999), American football player