Virtanen, who reached the second round at Wimbledon earlier this year, had already beaten Ugo Blanchet of France in straight sets and Great Britain's Jack Pinnington Jones in three sets in the qualifiers, which set up a match against former world number three Dimitrov.
However, the Bulgarian progressed to take his place in the main draw without a ball being served, as Virtanen was unable to recover in time from a back injury he sustained in the second set against Pinnington Jones, handing Dimitrov a walkover.
The ninth seed in qualifying battled through the pain to take the deciding set against the Brit, but was unable to recover in time, and therefore leaves Finland without a representative in men's or women's singles at the tournament in Queens.
A US Open semi-finalist in 2019, Dimitrov is looking to work his way back up the rankings after a pectoral injury at Wimbledon 2025 kept him out of action before inconsistent form on his return sees him currently ranked 140th, three places below Virtanen.