Singles
2021 Knoxville Challenger
Final
Champion	Christopher Eubanks
Runner-up	Daniel Altmaier
Score	6–3, 6–4
Events
Singles Doubles
← 2019 · Knoxville Challenger · 2022 →

Michael Mmoh was the defending champion^[1] but lost in the semifinals to Daniel Altmaier.

Christopher Eubanks won the title after defeating Altmaier 6–3, 6–4 in the final.

	Semifinals							Final
	8	Bjorn Fratangelo	5	5
		Christopher Eubanks	7	7
									Christopher Eubanks	6	6
								2	Daniel Altmaier	3	4
		Michael Mmoh	6	3	4
	2	Daniel Altmaier	3	6	6

	First round							Second round							Quarterfinals							Semifinals
	1	T Sandgren	6	63	64
	Alt	P Polansky	3	77	77			Alt	P Polansky	6	62	0r
	WC	Em Nava	6	6				WC	Em Nava	2	77	0
	Q	D Young	3	2											WC	Em Nava	4	4
	Q	G Brouwer	5	6	7										8	B Fratangelo	6	6
	Q	JC Aragone	7	2	5			Q	G Brouwer	3	6	3
		Yo Watanuki	4	65				8	B Fratangelo	6	3	6
	8	B Fratangelo	6	77																		8	B Fratangelo	5	5
	3	V Pospisil	6	2	3																		C Eubanks	7	7
		C Eubanks	2	6	6				C Eubanks	6	2	77
		G Soeda	6	78					G Soeda	3	6	64
	Alt	M Jaziri	4	66												C Eubanks	6	711
		J Jung	6	6											Alt	C Harrison	3	69
		J Kubler	4	1					J Jung	6	63	2r
	Alt	C Harrison	6	6				Alt	C Harrison	3	77	4
	6	J. J. Wolf	2	3

	First round							Second round							Quarterfinals							Semifinals
	7	D Popko	4	5
	Q	A McHugh	6	7				Q	A McHugh	6	6
		A Vukic	3	6	5				S Kozlov	4	4
		S Kozlov	6	4	7										Q	A McHugh	6	3	1
		Y Uchiyama	5	3												M Mmoh	3	6	6
		M Mmoh	7	6					M Mmoh	77	1	6
	PR	T Ito	64	3				4	M Krueger	64	6	2
	4	M Krueger	77	6																			M Mmoh	6	3	4
	5	J Sock	77	7																		2	D Altmaier	3	6	6
	WC	A Kovacevic	64	5				5	J Sock	6	77
		P Gunneswaran	6	77					P Gunneswaran	3	61
		M Torpegaard	2	62											5	J Sock	6	5	62
		B Rola	6	77											2	D Altmaier	3	7	77
		T-S Kwiatkowski	3	65					B Rola	63	4
	WC	A Walton	3	2				2	D Altmaier	77	6
	2	D Altmaier	6	6

• Main draw
• Qualifying draw