Singles
2021 Belgrade Open
Final
Champion	Novak Djokovic
Runner-up	Alex Molčan
Score	6–4, 6–3
Events
Singles Doubles
Belgrade Open · 2024 →

This was the first edition of the tournament, primarily created due to the one-week delay of the 2021 French Open.^[1]

Novak Djokovic won the title, defeating Alex Molčan in the final, 6–4, 6–3.^[2] It was Djokovic's third title ever in a tournament held in Serbia (excluding the Davis Cup).

The top four seeds receive a bye into the second round.

	Semifinals							Final
	1	Novak Djokovic	6	4	6
	Q	Andrej Martin	1	6	0
								1	Novak Djokovic	6	6
								Q	Alex Molčan	4	3
	Q	Alex Molčan	4	6	6
	8	Federico Delbonis	6	4	4

	First round							Second round							Quarterfinals							Semifinals
								1	N Djokovic	6	77
	LL	M Moraing	4	79	7			LL	M Moraing	2	64
		E Gerasimov	6	67	5										1	N Djokovic	6	6
	WC	M Topo	6	2	0										Alt	F Coria	1	0
	Alt	F Coria	4	6	6			Alt	F Coria	6	6
		P Cuevas	6	6					P Cuevas	3	2
	7	M Kecmanović	3	2																		1	N Djokovic	6	4	6
																						Q	A Martin	1	6	0
								3	N Basilashvili	1	6	64
	Q	C O'Connell	6	67	5			Q	A Martin	6	4	77
	Q	A Martin	3	79	7										Q	A Martin	3	6	6
		T Sandgren	4	2											5	D Lajović	6	3	4
		J Chardy	6	6					J Chardy	3	4
		R Berankis	3	3				5	D Lajović	6	6
	5	D Lajović	6	6

	First round							Second round							Quarterfinals							Semifinals
	Q	A Molčan	6	6
	WC	H Međedović	4	3				Q	A Molčan	6	6
	WC	P Krstin	6	3	6			WC	P Krstin	0	0
		S-w Kwon	2	6	1										Q	A Molčan	6	6
		L Pouille	5	2												F Verdasco	2	0
		F Verdasco	7	6					F Verdasco	77	6
								4	A Mannarino	64	0
																						Q	A Molčan	4	6	6
	8	F Delbonis	3	6	6																	8	F Delbonis	6	4	4
	LL	L Klein	6	3	4			8	F Delbonis	78	3	6
		R Albot	2	2					T Monteiro	66	6	4
		T Monteiro	6	6											8	F Delbonis	w/o
	SE	A Rinderknech	0	4											Q	R Carballés Baena
	Q	R Carballés Baena	6	6				Q	R Carballés Baena	6	3	77
								2	G Monfils	1	6	64

	First round							Qualifying competition
	Alt	John-Patrick Smith	4	65
	WC	Carlos Gómez-Herrera	6	77
								WC	Carlos Gómez-Herrera	3	68
								8	Alex Molčan	6	710
	Alt	Nerman Fatić	4	1
	8	Alex Molčan	6	6

	First round							Qualifying competition
	2	Roberto Carballés Baena	6	6
		Mirza Bašić	2	3
								2	Roberto Carballés Baena	6	6
								7	Vít Kopřiva	4	4
		Alexey Vatutin	3	6	4
	7	Vít Kopřiva	6	3	6

	First round							Qualifying competition
	3	Andrej Martin	6	6
		Akira Santillan	3	3
								3	Andrej Martin	6	6
								5	Mats Moraing	1	3
		Malek Jaziri	3	4
	5	Mats Moraing	6	6

	First round							Qualifying competition
	4	Christopher O'Connell	6	6
		Darian King	1	3
								4	Christopher O'Connell	79	7
								6	Lukáš Klein	67	5
	WC	Marko Tepavac	4	1
	6	Lukáš Klein	6	6

• Main draw
• Qualifying draw