| Doubles | |
|---|---|
| 2021 Sofia Open | |
| Champions |  Jonny O'Mara Ken Skupski |
| Runners-up |  Oliver Marach Philipp Oswald |
| Score | 6–3, 6–4 |
| Draw | 16 |
| Seeds | 4 |
Jamie Murray and Neal Skupski were the defending champions, [1] but chose to compete in San Diego with different partners instead.
Jonny O'Mara and Ken Skupski won the title, defeating Oliver Marach and Philipp Oswald in the final, 6–3, 6–4.
Henri Kontinen / 
Ben McLachlan (first round)
Tomislav Brkić / 
Nikola Ćaćić (quarterfinals) Oliver Marach / Philipp Oswald (final)
Luke Saville / John-Patrick Smith (quarterfinals)| First round | Quarterfinals | Semifinals | Final | ||||||||||||||||||||||||
| 1 | H Kontinen B McLachlan | 6 | 64 | [6] | |||||||||||||||||||||||
 J Erlich D Inglot | 4 | 77 | [10] | J Erlich D Inglot | 2 | 5 | |||||||||||||||||||||
 R Jebavý  M Middelkoop | 6 | 6 | R Jebavý M Middelkoop | 6 | 7 | ||||||||||||||||||||||
| WC |  A Andreev A Lazarov | 2 | 4 | R Jebavý M Middelkoop | 3 | 1 | |||||||||||||||||||||
| 4 | L Saville J-P Smith | 77 | 77 | J O'Mara K Skupski | 6 | 6 | |||||||||||||||||||||
 A Göransson  H Nys | 64 | 62 | 4 | L Saville J-P Smith | 3 | 6 | [8] | ||||||||||||||||||||
| WC | A Donski D Kuzmanov | 6 | 5 | [7] | J O'Mara K Skupski | 6 | 2 | [10] | |||||||||||||||||||
| J O'Mara K Skupski | 2 | 7 | [10] | J O'Mara K Skupski | 6 | 6 | |||||||||||||||||||||
 L Musetti A Vavassori | 3 | 68 | 3 | O Marach P Oswald | 3 | 4 | |||||||||||||||||||||
 M Demoliner R Matos | 6 | 710 | M Demoliner R Matos | 66 | 63 | ||||||||||||||||||||||
 R Bopanna  A-u-H Qureshi | 2 | 77 | [7] | 3 | O Marach P Oswald | 78 | 77 | ||||||||||||||||||||
| 3 | O Marach P Oswald | 6 | 61 | [10] | 3 | O Marach P Oswald | 2 | 7 | [10] | ||||||||||||||||||
 S González  A Molteni | 6 | 6 | S González A Molteni | 6 | 5 | [6] | |||||||||||||||||||||
| Alt | P Milushev R Shandarov | 3 | 4 | S González A Molteni | 65 | 6 | [10] | ||||||||||||||||||||
 A Golubev A Nedovyesov | 3 | 77 | [7] | 2 | T Brkić N Ćaćić | 77 | 2 | [4] | |||||||||||||||||||
| 2 | T Brkić N Ćaćić | 6 | 62 | [10] | |||||||||||||||||||||||
Johan Brunström and Raven Klaasen were the defending champions but decided not to participate.
Jürgen Melzer and Philipp Petzschner were the defending champions, but decided not to compete.
Christopher Kas and Oliver Marach were the defending champion, but decided not to compete.
João Sousa was the defending champion, but lost to Benjamin Becker in the first round.
Kei Nishikori won the title, defeating Julien Benneteau in the final, 7–6(7–4), 6–4.
Florin Mergea and Oliver Marach were the defending champions, but they did not participate.
Juan Sebastián Cabal and Robert Farah were defending champions, but lost to Martin Kližan and Philipp Oswald in the semifinals.
Kližan and Oswald went on to win the title, defeating Pablo Andújar and Oliver Marach in the final, 7–6(7–3), 6–4.
This is the first edition of the tournament.
Radu Albot and Dušan Lajović won the title, defeating Robert Lindstedt and Jürgen Melzer in the final, 6–4, 7–6(7–2).
Oliver Marach and Florin Mergea were the defending champions. Mergea did not participate this year, Marach partnered fellow Austrian Philipp Oswald.
Julio Peralta and Horacio Zeballos were the defending champions, but chose to compete in Hamburg instead.
Marcin Matkowski and Aisam-ul-Haq Qureshi were the defending champions, but lost in the quarterfinals to Raven Klaasen and Michael Venus.
Jamie Murray and Bruno Soares were the defending champions and successfully defended their title, defeating Bob and Mike Bryan in the final, 7–6(7–4), 7–5.
Oliver Marach and Mate Pavić were the defending champions, but chose not to defend their title.
Jürgen Melzer and Franko Škugor defeated Matwé Middelkoop and Frederik Nielsen in the final, 6–4, 7–6(8–6), to win the doubles tennis title at the 2019 Grand Prix Hassan II. They won their first title as a team, having never played together in a prior tournament. It marked Melzer's 15th individual doubles title and Škugor's fourth.
Robin Haase and Matwé Middelkoop were the defending champions, but Middelkoop chose to compete in Båstad instead.
Roman Jebavý and Andrés Molteni were the defending champions, but chose not to participate together. Jebavý played alongside Matwé Middelkoop but lost in the semifinals to Philipp Oswald and Filip Polášek. Molteni partnered Leonardo Mayer but lost in the first round to Oliver Marach and Jürgen Melzer.
Ivan Dodig and Filip Polášek were the defending champions but lost in the first round to Pablo Carreño Busta and Alex de Minaur.
Philipp Oswald and Filip Polášek were the defending champions, but chose to participate with different partners. Oswald partnered Marcus Daniell and lost in the quarterfinals to Marcel Granollers and Horacio Zeballos. Polášek partnered Ivan Dodig and lost in the semifinals to Austin Krajicek and Franko Škugor.
This was the third edition of the tournament, primarily created due to the one-week delay of the 2021 French Open.
Pierre-Hugues Herbert and Nicolas Mahut defeated Reilly Opelka and John Peers in the final, 6–4, 7–5, to win the doubles tennis title at the 2021 Queen's Club Championships. It was the duo's third title at the tournament. Opelka and Peers were contesting as a new pairing in their first final.
Robert Lindstedt and Jan-Lennard Struff were the reigning champions from when the tournament was last held in 2019, but chose not to participate this year.