A fight between the pair has been rumoured in recent months with WBA's secondary welterweight title holder Pacquiao keen to unify WBA by beating Thurman.
Pacquiao and Thurman will face off in a welterweight title fight on July 20 on FOX pay-per-view.
Pacquiao dominated Adrien Broner for 12 rounds in his last bout on January 19 at MGM Grand Garden Arena in Las Vegas.
Pacquiao-Thurman will take place in Las Vegas, a PBC source told ESPN, but no site was formally announced and likely won't be until a news conference with the fighters in the next couple of weeks.
"The summer just got a little hotter", said Pacquiao as he tweeted their fight poster.
Thurman is the WBA "super" welterweight champion, while Pacquiao holds the "regular" title.
Thurman has a ideal record of 29 wins from 29 bouts but fans are unsure if he will continue that against a fighter with as much experience as Pacquiao.
The 30-year old Thurman (29-0, 22 KO), a native of Clearwater, Florida, is coming off a near-two year absence with a unanimous decision win over Joselito Lopez to retain the WBA crown.
In Thurman he'll be taking on the WBA's "super world champion" in the division.
"Manny Pacquiao is not going to be here for the years to come".
Pacquiao, 40, most recently fought on January 19, where he beat Adrian Broner in a 12-round fight in Las Vegas. "If we get that fight, we'd be happy to do it for ourselves and the fans".
Thurman, for his part, last fought in January 2019, too.