The pop star took off his long-sleeved white top for the trek, revealing his tattoed and toned torso as he straddled the horse.
"Pure bred stallion," Justin captioned an Instagram snap of himself looking quite the cowboy in a brown fedora and reflective aviator sunglasses.
Justin also wore a pair of pale baggy jeans and a casual pair of black boots for the horse ride.
Just the day before, the Baby singer spent quality time with his mum for Mother's Day, taking her for a special dinner at the Four Seasons Hotel.
"My mom has taught me how to love, forgive and believe. She is my everything ♛" he wrote on Twitter.
The Canadian singer appears unfazed at his recent brushes with the law.
He is understood to have caused more than $20,000 worth of damage to his neighbour's property during the alleged egg attack on the Calabasas residence in January, for which a chief investigating officer has said he "deserves a felony".
And he was held for four hours by customs officials after touching down in LA at the end of April.
Justin was arriving back in the US from Tokyo with his entourage, but was temporarily detained at LAX for "routine secondary questioning".
"It's standard, especially after he has had other legal issues in the US in the past," a source told US Weekly.