See main article: article and 2021 Erste Bank Open.
Łukasz Kubot and Marcelo Melo were the defending champions,[1] but Kubot chose not to participate. Melo played alongside Ivan Dodig, but lost in the first round to Feliciano López and Stefanos Tsitsipas.
Juan Sebastián Cabal and Robert Farah won the title, defeating Rajeev Ram and Joe Salisbury in the final, 6–4, 6–2.