The 2021 TK Sparta Prague Open was a professional tennis tournament played on clay courts. It was part of the 2021 ATP Challenger Tour. It took place in Prague, Czech Republic between 9 and 15 August 2021.

Country	Player	Rank1	Seed
SRB	Nikola Milojević	161	1
KAZ	Dmitry Popko	183	2
ITA	Lorenzo Giustino	234	3
ARG	Facundo Mena	254	4
CHI	Nicolás Jarry	263	5
ITA	Riccardo Bonadio	271	6
ESP	Adrián Menéndez Maceiras	287	7
CZE	Michael Vrbenský	288	8

• ¹ Rankings as of 2 August 2021.^[1]

The following players received wildcards into the singles main draw:

• Toby Kodat
• Martin Krumich
• Dalibor Svrčina

The following player received entry into the singles main draw using a protected ranking:

• Gerald Melzer

The following players received entry from the qualifying draw:

• Franco Agamenone
• Adrian Andreev
• Geoffrey Blancaneaux
• Emilio Nava

• Dalibor Svrčina def. Dmitry Popko 6–0, 7–5.

• Jonáš Forejtek / Michael Vrbenský def. Evgeny Karlovskiy / Evgenii Tiurnev 6–1, 6–4.