The deal is pending a physical. Pitcher Gil Meche is the only Seattle player left eligible for arbitration.
Seattle used Bloomquist's versatility last season, when the 28-year-old played at first (one game), second (32 games), third (six games), shortstop (24 games) and the outfield (15 games).
Bloomquist had career highs in at-bats (249), batting average (.257), doubles (15), RBI (22) and stolen bases (14) last season. He is hitting .261 in 267 career games.
"He helps us in a variety of roles, including the ability to steal a base and play almost any position on the field," general manager Bill Bavasi said.
Bloomquist tied a team record with three doubles on July 6 against Kansas City, but his season ended early after he was placed on the disabled list Aug. 30 with a strained left hamstring.