The international 400m runner from York was part of Great Britain's gold-medal-winning relay team at the European Indoor Championships in 2013.
The 28-year-old has recently divided his time between running and filming but has now announced he is leaving the athletics track for good.
He will take up a place on an acting course in Birmingham in September.
Buck, whose personal best of 45.61 secs was set in 2012,  said his last scheduled race was on 5 August in Copenhagen.
He is also running on 18 July in Loughborough, "which looks like being my last international UK-based race, unless I get any offers to run elsewhere," he said.
"I will be seeing this season through to the end before hanging up my spikes."
In a statement, Buck said: "In accepting this place on the Acting Masters at Birmingham School of Acting, I will also be retiring as an athlete.
"It was always my plan to run through until Rio 2016 or London 2017, however, I always said that I'd be flexible to other opportunities which came my way.
"Although this has been a tough decision, I feel that it is the right one. I believe you've got to give yourself entirely to your pursuits, and so I had to make my decision."
Buck lost his funding from UK Athletics in October 2011 and took up shop work to make up the Â£20,000 for training camps.
Athlete Richard Buck has announced he is retiring from athletics to pursue a career as an actor.