Kevin Krawietz and Horia Tecău defeated Félix Auger-Aliassime and Hubert Hurkacz in the final, 7–6^(7–4), 6–4, to win the doubles tennis title at the 2021 Halle Open. It was their first title as a team.^[1]

Raven Klaasen and Michael Venus were the defending champions from when the event was last held in 2019,^[2] but they did not defend their title together. Klaasen played alongside Ben McLachlan but lost in the second round to Andrés Molteni and Guido Pella.^[3] Venus played alongside Tim Pütz but lost in the semifinals to Auger-Aliassime and Hurkacz.^[4]

	Semifinals							Final
	5	Tim Pütz Michael Venus	64	2
		Félix Auger-Aliassime Hubert Hurkacz	77	6
									Félix Auger-Aliassime Hubert Hurkacz	64	4
								3	Kevin Krawietz Horia Tecău	77	6
	3	Kevin Krawietz Horia Tecău	78	7
	6	Sander Gillé Joran Vliegen	66	5

	First round							Second round							Quarterfinals							Semifinals
								1	I Dodig F Polášek	7	1	[6]
	Q	D Masur R Molleker	3	5					A Krajicek S Querrey	5	6	[10]
		A Krajicek S Querrey	6	7												A Krajicek S Querrey	3	4
		M Demoliner S González	65	3											5	T Pütz M Venus	6	6
	LL	Y Hanfmann D Koepfer	77	6				LL	Y Hanfmann D Koepfer	62	2
								5	T Pütz M Venus	77	6
																						5	T Pütz M Venus	64	2
																							F Auger-Aliassime H Hurkacz	77	6
								4	W Koolhof J-J Rojer	65	3
		K Khachanov A Rublev	3	6	[5]				F Auger-Aliassime H Hurkacz	77	6
		F Auger-Aliassime H Hurkacz	6	4	[10]											F Auger-Aliassime H Hurkacz	6	6
		J Erlich L Harris	5	77	[10]											J Erlich L Harris	3	4
		S Bolelli M González	7	63	5				J Erlich L Harris	6	6
								8	O Marach A-u-H Qureshi	3	3

	First round							Second round							Quarterfinals							Semifinals
								7	R Klaasen B McLachlan	64	66
		A Molteni G Pella	78	4	[10]				A Molteni G Pella	77	78
	WC	D Altmaier D Stricker	66	6	[7]											A Molteni G Pella	4	2
		T Brkić N Ćaćić	4	6	[10]										3	K Krawietz H Tecău	6	6
	WC	D Brown J-L Struff	6	4	[7]				T Brkić N Ćaćić	63	3
								3	K Krawietz H Tecău	77	6
																						3	K Krawietz H Tecău	78	7
																						6	S Gillé J Vliegen	66	5
								6	S Gillé J Vliegen	77	6
		L Saville J Thompson	6	6					L Saville J Thompson	64	3
		F Nielsen F Škugor	3	4											6	S Gillé J Vliegen	6	77
		R Bopanna D Sharan	78	6												R Bopanna D Sharan	3	63
		R Albot N Basilashvili	66	4					R Bopanna D Sharan	713	6
								2	Ł Kubot É Roger-Vasselin	611	4

1. Daniel Masur / Rudolf Molleker

1. Yannick Hanfmann / Dominik Koepfer

	First round							Qualifying competition
	1	Evan King Hunter Reese	4	64
	WC	Daniel Masur Rudolf Molleker	6	77
								WC	Daniel Masur Rudolf Molleker	5	77	[10]
									Yannick Hanfmann Dominik Koepfer	7	65	[6]
		Yannick Hanfmann Dominik Koepfer	6	77
	2	André Göransson Sebastian Korda	2	63

• Main draw
• Qualifying draw