According to STV, the Paisley club are on the verge of offering the 30-year-old a contract who is believed to be training with the Premiership side this week.
Along with Birmingham City the winger has turned out for Sheffield United, Swansea and Wigan Athletic.The Welsh international has been a free agent since he parted ways with Indian Super League club ATK.
Cotterill has racked up 55 goals in 430 games since he began his career at Bristol City fourteen years ago.
Kearney's second signing
The move would represent Oran Kearney's second signing since he took over from Alan Stubbs last week.
Kearney has already signed former QPR player Anton Ferdinand who earned a clean sheet on Friday night against league champions Celtic.
The news that Kearney is moving in on his latest signing comes as the Buddies reached an agreement to appoint former manager Gus McPherson as technical director.