Doubles
2021 Open de Oeiras II
Final
Champions	Nuno Borges Francisco Cabral
Runners-up	Pavel Kotov Tseng Chun-hsin
Score	6–1, 6–2
Events
Singles Doubles
← 2021 · Open de Oeiras · 2021 →

This was the second of four editions of the tournament in the 2021 ATP Challenger Tour calendar.^[1]

Mats Moraing and Oscar Otte were the defending champions but withdrew from the tournament before their first round match.

Nuno Borges and Francisco Cabral won the title after defeating Pavel Kotov and Tseng Chun-hsin 6–1, 6–2 in the final.

	First round							Quarterfinals							Semifinals							Final
	1	E Couacaud M Guinard	6	6
		D-h Lee G Oliveira	0	2				1	E Couacaud M Guinard	3	7	[6]
		N Chappell V Orlov	w/o						N Chappell V Orlov	6	5	[10]
		M Moraing O Otte														N Chappell V Orlov	2	1
	4	Gonçalo Falcão D Yevseyev	6	4	[9]											N Borges F Cabral	6	6
		M Rosenkranz Tom Schönenberg	3	6	[11]				M Rosenkranz T Schönenberg	65	1
		N Borges F Cabral	6	6					N Borges F Cabral	77	6
	WC	Eduardo Morais Vasco Prata	1	3																			N Borges F Cabral	6	6
	WC	Miguel Gomes H Rocha	1	2																			P Kotov C-h Tseng	1	2
		E Escobedo L Miedler	6	6					E Escobedo L Miedler	w/o
		R Brancaccio Eduard Esteve Lobato	2	6	[10]				R Brancaccio E Esteve Lobato
	3	H Johnson Y Johnson	6	2	[5]											E Escobedo L Miedler	6	2	[6]
	WC	J Faria Tiago Torres	2	4												P Kotov C-h Tseng	4	6	[10]
		P Kotov C-h Tseng	6	6					P Kotov C-h Tseng	6	6
		GM Moroni R Ortega Olmedo						2	H Bourchier S Galdós	4	4
	2	H Bourchier S Galdós	w/o

• Main draw