The 25-year-old joined the Chiefs from Welsh club Ospreys in 2017 and has scored 15 tries in 39 appearances.
He crossed for the opening touchdown in Exeter’s most recent game, a 57-20 win over Bath on 7 March.
O’Flaherty is the sixth player to agree a new deal with the club since the season was put on hold because of the coronavirus pandemic.
“It’s tough for everyone at the moment. Personally, I can’t wait to get back amongst the lads, having a laugh, training hard and getting out on the pitch again,” he told the club website.
“Hopefully, rugby gets going sooner rather than later. When it does, though, I know all of us at the Chiefs will be ready and raring to go.”
On 8 April, Premiership Rugby said it remained committed to “completing all games” in the 2019-20 season.
There are nine rounds of regular-season action remaining, with the Twickenham final planned for 20 June having been postponed.
Exeter hold a five-point lead over Sale at the top of the table, with Bristol two points further back in third.