The Big Rig is putting it in park.
The decision, made along with family and doctors, was a result of a back injury that kept him off the ice for the entirety of the 2015-16 season.
The Senators concurrently announced Phillips will remain with the organization in a front office position. He will continue to engage with the Ottawa-Gatineau community while being involved in community programs, alumni relations, and business development.
Drafted first overall by the Senators in 1996, Phillips made the jump to the NHL at age 19, and went on to appear in 1,179 games with the club, setting a franchise record.
Former and current general managers Bryan Murray and Pierre Dorion were in attendance when Phillips made the announcement Thursday, and praised his time with the club.
"He's been a leader in our dressing room, a leader in our community and he’s had a great career," said Dorion, who also listed off the 20-plus charities Phillips is involved with in the community. "He represents loyalty and what it means to be an Ottawa Senator."
A prototypical stay-at-home defenseman, Phillips scored 71 goals and added 218 assists over the course of his career.
He also appeared in 114 playoff games for the Senators, where he helped the team reach the Stanley Cup Final for the first and only time in 2007 - which they lost to Anaheim in five games - and recorded his most memorable goal in a 2003 series against New Jersey.