Doubles
2021 Open de Rennes
Final
Champions	Bart Stevens Tim van Rijthoven
Runners-up	Marek Gengel Tomáš Macháč
Score	6–7(2–7), 7–5, [10–3]
Events
Singles Doubles
← 2020 · Open de Rennes · 2022 →

Antonio Šančić and Tristan-Samuel Weissborn were the defending champions^[1] but chose not to defend their title.

Bart Stevens and Tim van Rijthoven won the title after defeating Marek Gengel and Tomáš Macháč 6–7^(2–7), 7–5, [10–3] in the final.

	First round							Quarterfinals							Semifinals							Final
								1	D Pel A-u-H Qureshi	62	63
		M Gengel T Macháč	65	6	[10]				M Gengel T Macháč	77	77
		T Kamke Y Maden	77	2	[8]											M Gengel T Macháč	77	6
	3	M Guinard A Olivetti	7	3	[7]											T Lamasine G Simon	65	1
		T Lamasine G Simon	5	6	[10]				T Lamasine G Simon	6	6
		T Matsui K Uesugi	1	64					A Kadhe B Schnur	0	4
		A Kadhe B Schnur	6	77																			M Gengel T Macháč	77	5	[3]
		L Broady S Stakhovsky																					B Stevens T van Rijthoven	62	7	[10]
		T Gabashvili M Janvier	w/o						T Gabashvili M Janvier	6	1	[5]
		K Jacquet H Mayot	4	5				4	J Nedunchezhiyan P Raja	3	6	[10]
	4	J Nedunchezhiyan P Raja	6	7											4	J Nedunchezhiyan P Raja	6	67	[8]
		Mats Hermans G Smits	6	6												B Stevens T van Rijthoven	4	79	[10]
		A Chandrasekar Davide Pozzi	1	3					M Hermans G Smits	3	2
		B Stevens T van Rijthoven	1	7	[10]				B Stevens T van Rijthoven	6	6
	2	H Nys A Rinderknech	6	5	[8]

• Main draw