"Kevin and Christine Costner have come to an amicable and mutually agreed upon resolution of all issues pertaining to their divorce proceedings," the couple said in a joint statement released on Tuesday by the actor's publicist.
The agreement ends what had become a contentious court fight, and lets the couple avoid a trial that had been scheduled for December in a Santa Barbara County, California court.
Baumgartner filed for divorce in May.
The two had already fought in court over child support payments. After a two-day hearing in which both Costner, 68, and Baumgartner, 49, took the stand to testify, a judge on September 8 ordered Costner to pay about $US63,000 ($A97,000) per month for their three children, People reported. Baumgartner had sought about $US175,000 ($A268,000) per month.
Costner and Baumgartner, a model and handbag designer, began dating in 1998 and married at his Colorado ranch in 2004.
They have two sons, ages 16 and 14, and a 12-year-old daughter together.
It was the second marriage for Costner, the Oscar and Emmy winning star of TV's Yellowstone and films including Dances With Wolves, The Bodyguard and Bull Durham.
He also has four adult children from previous relationships.
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