Halman went 3-for-5 and scored three times for the Rainiers.
The Netherlands native started his night early, slugging a three-run homer in the first inning against former Mariners starter John Halama.
He broke the game open in the sixth with a two-RBI double and capped off Tacoma's outburst with a two-run blast in the top of the ninth.
Halman's previous best was six RBIs for the Double-A West Tenn Diamond Jaxx against the Mississippi Braves on April 28, 2009.
Matt Mangini homered for the second straight game and drove in two runs. The third baseman has four homers and 12 RBIs in his last 10 games. Tommy Everidge also went yard and scored three times for the Rainiers (25-24), who have won four straight games.
Luke French (6-2) was the beneficiary of Tacoma's 14-hit attack. The former eighth-round pick allowed three runs on seven hits and struck out four over eight innings. Levale Speigner pitched a perfect ninth, fanning one.
Matt Carson hit a pair of solo homers for the River Cats (25-28). The loss snapped Sacramento's season-high six-game win streak.