Doubles
2021 Open de Oeiras III
Final
Champions	Hunter Reese Sem Verbeek
Runners-up	Sadio Doumbia Fabien Reboul
Score	4–6, 6–4, [10–7]
Events
Singles Doubles
← 2021 · Open de Oeiras · 2021 →

Nuno Borges and Francisco Cabral were the defending champions^[1] but lost in the semifinals to Hunter Reese and Sem Verbeek.

Reese and Verbeek won the title after defeating Sadio Doumbia and Fabien Reboul 4–6, 6–4, [10–7] in the final.

	First round							Quarterfinals							Semifinals							Final
	1	A-u-H Qureshi M Reid	2	6	[13]
		F Coria E Gómez	6	2	[15]				F Coria E Gómez	66	4
		S Johnson M Schnur	2	7	[10]				S Johnson M Schnur	78	6
		R Matos P Sousa	6	5	[7]											S Johnson M Schnur	62	3
	4	MÁ Reyes-Varela F Romboli	3	4												S Doumbia F Reboul	77	6
		R Jebavý J Veselý	6	6					R Jebavý J Veselý	2	711	[7]
		S Doumbia F Reboul	6	6					S Doumbia F Reboul	6	69	[10]
		H Dellien L Mayer	4	3																			S Doumbia F Reboul	6	4	[7]
		P Martínez B Zapata Miralles	3	6	[9]																		H Reese S Verbeek	4	6	[10]
	WC	N Borges F Cabral	6	3	[11]			WC	N Borges F Cabral	7	6
	WC	G Elias Gonçalo Falcão	1	3				3	R Arneodo S Walków	5	3
	3	R Arneodo S Walków	6	6											WC	N Borges F Cabral	4	4
	WC	J Domingues F Ferreira Silva	6	64	[8]											H Reese S Verbeek	6	6
		G Oliveira Y Uchiyama	1	77	[10]				G Oliveira Y Uchiyama	6	5	[3]
		H Reese S Verbeek	6	7					H Reese S Verbeek	2	7	[10]
	2	LD Martínez D Vega Hernández	1	5

• Main draw