By waiting until the start of the NFL's new year that began at 4 p.m. ET and designating Williams a post-June 1 cut, the Panthers will save approximately $2 million under the 2015 salary cap.
"DeAngelo will forever be remembered as one of the quintessential Panthers of this era," coach Ron Rivera said in a team release. "He holds all of our running back records and his 20 total touchdowns in the 2008 season was a truly special feat.
"I really enjoyed watching DeAngelo grow over the past four years and wish him nothing but the best moving forward."
This was merely a formality. Williams, 31, recently told Charlotte television station WBTV in an exclusive interview that Rivera and general manager Dave Gettleman informed him of their decision to release him prior to the NFL combine.
Stewart emerged as the team's leading rusher when Williams missed the final four regular-season games with a broken hand. Stewart finished the season with 809 yards during the regular season and another 193 yards in two playoff games.
Injuries limited Williams to six games in 2014.
There was no comment from Williams in the release. He said in his WBTV interview that would be his only statement on the matter. He said he wasn't bitter, but expressed disappointment that team owner Jerry Richardson didn't reach out to him when his mother died of breast cancer in May.
Williams led the NFL's breast cancer awareness movement when he learned a few years ago that his mother had the disease. He said the only member of the team to attend his mother's funeral was defensive end Greg Hardy, who was facing domestic violence charges at the time.
It was since revealed that fullback Mike Tolbert also attended.
"There was a couple of things that upset me about the Panthers when my mom died," Williams told WBTV. "Nobody came to the funeral. The owner didn't reach out. He didn't say anything."
Williams has been with the Panthers since they made him the 27th overall pick of the 2006 draft. He has 6,846 career yards rushing and 46 rushing touchdowns, both team records.
Williams' career 4.78-yards per carry average ranks second in team history and is 15th in NFL history among players with a minimum of 750 attempts.
"We are very appreciative of the hard work and effort that DeAngelo brought to Bank of America Stadium every day," general manager Dave Gettleman said in the release. "Last year was extremely difficult for him, but he finished the season like a pro and I will always respect him for that.”