Trevor Carson has joined St Mirren from Scottish Premiership rivals Dundee United for an undisclosed fee.
The Northern Ireland goalkeeper, 34, has agreed a two-year deal, describing the Buddies as "ambitious".
Carson worked with St Mirren manager Stephen Robinson at Motherwell and Morecambe, where he spent time on loan earlier this year.
He is the second former Fir Park player signed this summer by Robinson after midfielder Mark O'Hara, 26.
Carson has amassed 363 club appearances in England and Scotland and been capped seven times by his country.