Lamar Odom will try to revitalize his career back where he started it.
The Mavericks also will create their own trade exception worth $8.9 million by shedding Odom's contract without taking any salary back.
Dallas also received the draft rights to forward Tadija Dragicevic from Utah and cash considerations from the Houston Rockets. The Clippers sent the draft rights to second-round pick Furkan Aldemir to Houston.
Utah also received the draft rights to Shan Foster from the Mavericks.
All parties essentially had agreed to the deal Thursday, but it could not proceed until Williams made a firm decision on whether to pick up his $8.5 million option for next season, which he did Friday afternoon.
Williams' agent, Mark Bartelstein, stressed the delay had more to do with timing, not any issue Williams had playing for Utah, where he began his career in 2003.
"There was no blocking going on," Bartelstein said. "When you make a decision like this, you want to study it very closely.
"But the more we looked at it, the more excited we were about going back to Utah. Mo's very happy to be going back there."
In a text message to ESPNLosAngeles.com, Williams wrote: "It's where it all began. I'm excited about the opportunity."
Williams spoke with Jazz general manager Kevin O'Connor and coach Tyrone Corbin before opting into the final year of his deal. Williams must pass a physical but is expected to hold a news conference in Salt Lake City on Monday or Tuesday.
Dallas originally had until Friday to either pay $2.4 million to buy out Odom's $8.2 million salary for next season or have him on the books for 2012-13.
While Williams pondered his options, sources told ESPN.com's Marc Stein the Mavericks and Odom had agreed to extend the buyout deadline in Odom's contract until Saturday, leaving one more day to finalize the proposed three-way trade.
The Clippers are hoping Odom looks more like the player who won the Sixth Man of the Year Award with the Los Angeles Lakers in 2011, and not the enigmatic player who shot just 35 percent from the field and averaged a career-low 6.6 points for the Mavericks last season.
"No point looking in the rear-view mirror," Mavericks owner Mark Cuban told ESPNDallas.com. "... There are definitely advantages from a cap perspective."
Although he had asked to be traded by the Lakers after learning he'd been included in the failed trade for Chris Paul, Odom never settled in with the Mavericks. The Clippers are hoping a return to his home in Los Angeles will be enough for the 32-year-old forward to return to form.
Still, it will be an interesting homecoming for Odom. The Clippers originally drafted him No. 4 overall in 1999. He averaged 16.6 points as a rookie and 17.2 points in his second year but left rather unceremoniously in 2003-04 to join the Miami Heat.
Clippers coach Vinny Del Negro smiled when asked Thursday about Odom and the trade, but was not able to speak on the record until the deal was completed.
"I can't talk about other teams' players," Del Negro said. "But you know what a player of his caliber has done in this league. ...
"We'll figure all that out (Friday). Hopefully, we can finish out the things that we've been working on and move the team in the right direction for what's best for everyone. There's still a lot of work to be done, and we'll move forward in that direction. Obviously, tomorrow is a very important day."
The 6-foot-9 Dragicevic was picked 53rd overall by Utah in the 2008 draft. The Serbia native averaged 10.6 points for Angelico Biella in Italy last season. Foster was the 51st overall selection in the 2008 draft by the Mavericks after he was a top scorer at Vanderbilt. He played for Belfius Mons-Hainaut in Belgium last season.
Aldemir, from Turkey, was the Clippers' only draft pick Thursday night at No. 53.
ESPN.com senior NBA writer Marc Stein, ESPNDallas.com's Jeff Caplan and The Associated Press contributed to this report.