The 27-year old, who scored 14 SPL goals last season, was out of contract after spending two seasons in Paisley and admits it is a favourable move to join the Steelmen at Fir Park.
"I am really pleased to be here and I can't wait to get going," Higdon told the club's official website.
"Last season went very well for me. It was just unfortunate it had to end when it did because when you are scoring goals, you just want the games to keep coming.
"It was hard to leave St Mirren as I really enjoyed my time there. They are a good club and I wish them all the best for the future.
"However, the opportunity to work with Stuart McCall was a big attraction. A lot of people I know in football speak very highly of him and the club certainly seem to be progressing and heading in the right direction."