Anderson took 50 wickets at 17 in 2026, yet Lancashire decided not to offer him a new contract for 2027.
The 44‑year‑old captained the side for the first time last season, steering a struggling Division Two squad with both pace and experience.
In a raw tweet, Anderson wrote, "I've supported Lancashire since I was a kid and so to play for them for 25 years was a dream come true. I have always found it special walking out to play at Old Trafford. If it was up to me it wouldn't have ended like this."
His exit follows the England board's decision to drop him two years ago, a move that left the former Test legend in limbo. For the club, the loss of a 44‑year‑old captain and record‑holder means a rebuild.
Lancashire will face Derbyshire in the opening fixture of the 2027 County Championship, while Anderson may look to join another county or contemplate retirement.