Rumors of Costner's exit from the beloved show first surfaced in February.
Costner told the court on Friday that the studios behind Yellowstone had failed to strike a deal ensuring his participation, multiple reports stated Tuesday.
"I couldn’t help them anymore," he said, People reported. "We tried to negotiate, they offered me less money than previous seasons, there were issues with the creative."
Per USA Today, it was ultimately a disagreement over splitting season 5 into two parts that finalized Costner's decision to leave. He referred to the disagreement as a "long, hard-fought negotiation," adding that he was disappointed with where the talks concluded.
"I've been told it’s a little disappointing that (it's) the number one show on TV (and) I'm not participating,” Costner said. "I'll probably go to court over it."
ET exclusively reported in May that Costner would not be returning to Yellowstone due to disagreements over his filming schedule. Costner portrayed the patriarch, John Dutton, in Yellowstone, and its monumental success spawned two prequels -- 1883 and 1923, respectively.
Costner is in court amid a suit against his estranged wife, Christine Baumgartner, to settle their bitter dispute over how much Costner should have to pay in monthly child support for their three children -- sons Cayden, 16, and Hayes, 14, and daughter Grace, 13. Baumgartner filed for divorce in May after 18 years of marriage.
On Friday, the judge ruled in Costner's favor and agreed he should only have to pay his estranged wife $63,209 a month in child support, drastically less than what she requested
The child support payments will go into effect Friday. After the court ordered the reduction in child support, Baumgartner looked stunned but did not offer any emotion beyond that. As for Costner, he seemed happy with the court order. After a quick huddle with his lawyers, Costner -- flanked by police -- was escorted out of the Santa Barbara County courtroom.