Marcel Granollers and Horacio Zeballos defeated Nikola Mektić and Mate Pavić in the final, 1–6, 6–3, [10–8], to win the men's doubles tennis title at the 2021 Madrid Open. It was the third-seeded duo's third ATP Tour Masters 1000 doubles title together. Mektić and Pavić were contending to be the first doubles team in five years to win a season's first three Masters 1000 events.[1]
Pavić and Robert Farah were in contention for the ATP No. 1 doubles ranking at the start of the tournament. Pavić retained the top ranking after Farah lost in the second round.
Seeds
The top four seeds received a bye into the second round.