Hill, who is averaging is 11.8 points this season, was sent by the Thunder to the Sixers in exchange for Tony Bradley and second-round picks in 2025 and 2026. The 76ers also get Iggy Brazdeikis from the Knicks.
Terrance Ferguson, meanwhile, ultimately heads from the Thunder to the Knicks, while Austin Rivers goes from the Knicks to Oklahoma City. The Knicks also picked up Vincent Poirier and a 2021 second-round pick from the Sixers, with sources telling ESPN that New York is planning to waive the 7-footer.
Oklahoma City now has a projected 34 draft picks over the next seven years -- 17 first-round picks and 17 second-rounders.
Hill, 34, provides Sixers coach Doc Rivers with a two-way guard that can be a part of closing lineups for the Eastern Conference leaders. Hill, who has been out for two months after undergoing hand surgery in late January, has played both on and off the ball in his career, making him an ideal backcourt partner for Philadelphia star Ben Simmons.
76ers president of basketball operations Daryl Morey said he feels "really good about the roster we have."
"I think we upgraded ourselves a lot today," Morey said. "And we're gonna be one of the top few teams to win the title."
Hill also has a lightly guaranteed contract for next season -- which Philadelphia could either guarantee and keep on its books or use in a trade, or cut him to reduce its payroll.
He is in his 13th NBA season and will be joining his eighth team -- and fifth in three seasons -- after stints with San Antonio, Indiana, Utah, Cleveland, Sacramento, Milwaukee and Oklahoma City. He has averaged 11.1 points during his career while shooting 38% from 3-point range.
Bradley, who played his first three NBA seasons in Utah, was averaging 5.5 points and 5.2 rebounds for Philadelphia this season.
Rivers, the No. 10 overall pick by New Orleans in 2012, was averaging 7.3 points for the Knicks this season. He also has played for the Clippers, Rockets and Wizards during his nine NBA seasons.
ESPN's Tim Bontemps contributed to this report.