Motter has made the Mariners' 25-man roster, Greg Johns of MLB.com reports.
The versatile 27-year-old parlayed a strong spring into a spot on the Opening Day roster. Motter hit .293 with three doubles, three home runs and 11 RBI over 70 plate appearances this spring after a forgettable cup of coffee with the Rays last season when he slashed just .188/.290/.300. His ability to play up to seven positions and Shawn O'Malley's current absence due to a recent appendectomy likely helped seal the deal for Motter, who is also a stolen-base threat and has three seasons with more than 20 thefts on his minor-league resume.