2021 UCI Road World Championships – Men's under-23 time trial

The Men's under-23 time trial of the 2021 UCI Road World Championships was a cycling event that took place on 20 September 2021 from Knokke-Heist to Bruges, Belgium. It was the 25th edition of the event. The race was won by Danish rider Johan Price-Pejtersen, finishing ten seconds ahead of Luke Plapp of Australia.

Final classification
68 riders from 43 nations entered the competition, of which one did not finish and oone did not start.