Singles
2021 San Marino Open
Final
Champion	Holger Rune
Runner-up	Orlando Luz
Score	1–6, 6–2, 6–3
Events
Singles Doubles
← 2014 · San Marino Open · 2022 →

Adrian Ungur was the defending champion when the event was last held in 2014^[1] but chose not to defend his title as he had retired from professional tennis.

Holger Rune won the title after defeating Orlando Luz 1–6, 6–2, 6–3 in the final.

	Semifinals							Final
	1	Marco Cecchinato	5	64
		Holger Rune	7	77
									Holger Rune	1	6	6
								Q	Orlando Luz	6	2	3
	4	Hugo Dellien	4	2
	Q	Orlando Luz	6	6

	First round							Second round							Quarterfinals							Semifinals
	1	M Cecchinato	77	6
		P Lorenzi	63	2				1	M Cecchinato	77	78
	WC	R Brancaccio	4	4				WC	L Nardi	64	66
	WC	L Nardi	6	6											1	M Cecchinato	77	6
		R Marcora	78	77											LL	P Kotov	65	3
		A Pellegrino	66	61					R Marcora	4	4
	LL	P Kotov	77	77				LL	P Kotov	6	6
	5	F Gaio	62	63																		1	M Cecchinato	5	64
	3	S Caruso	3	6	6																		H Rune	7	77
		Q Halys	6	2	2			3	S Caruso	6	64	2
	PR	J Cagnina	3	4					H Rune	2	77	6
		H Rune	6	6												H Rune	6	7
		J Menezes	5	6	6											J Menezes	0	5
		G Elias	7	4	4				J Menezes	62	77	711
		GM Moroni	6	3	5			Q	F Forti	77	62	69
	Q	F Forti	4	6	7

	First round							Second round							Quarterfinals							Semifinals
	7	S Báez	64	7	5
		J Clarke	77	5	7				J Clarke
		B Gojo	5	2					F Meligeni Alves	w/o
		F Meligeni Alves	7	6												F Meligeni Alves	3	2
		R Olivo	64	4											4	H Dellien	6	6
		M Copil	77	6					M Copil	6	5	4
	Q	Manuel Mazza	4	5				4	H Dellien	4	7	6
	4	H Dellien	6	7																		4	H Dellien	4	2
	8	B Rola	6	6																		Q	O Luz	6	6
		Z Kolář	3	3				8	B Rola	6	4	2
	Alt	M Jaziri	3	2r				Q	O Luz	4	6	6
	Q	O Luz	6	4											Q	O Luz	79	7
		M Janvier	6	6												M Janvier	67	5
	Q	J Ocleppo	2	3					M Janvier	7	6
	WC	M De Rossi	3	3				2	G Simon	5	1
	2	G Simon	6	6

• Main draw
• Qualifying draw