The 2018 Sofia Open (also known as 2018 DIEMA XTRA Sofia Open for sponsorship reasons)[3] was a men's tennis tournament played on indoor hard courts.

It was the third edition of the Sofia Open as part of the ATP World Tour 250 series of the 2018 ATP World Tour.

It took place at the Arena Armeec in Sofia, Bulgaria, from 5 February until 11 February 2018.

Unseeded Mirza Bašić, who entered the main draw as a qualifier, won the singles title.

[4] The following players received wildcards into the singles main draw: The following players received entry from the qualifying draw: The following players received entry as a lucky loser: The following pairs received wildcards into the doubles main draw: The following pair received entry as alternates: