League One-bound MK Dons will sign midfielder Ed Upson on 1 July when his contract with Millwall expires.
The 26-year-old ex-Yeovil man has been a Lions player since 2014, but was one of seven to be released after the League One play-off final loss.
He made 39 appearances for Neil Harris' side last season and has signed a two-year deal at Stadium:MK.
Upson becomes Karl Robinson's first summer signing as he prepares for life back in the third tier.
Find all the latest football transfers on our dedicated page.