On December 14, 2009, Alfonzo signed a minor league contract with the Seattle Mariners. On May 28, 2010, his contract was purchased by the Mariners after Josh Bard was placed on the DL. He made his Mariner debut two days later against the Los Angeles Angels of Anaheim, going 3 for 5 with a home run and 4 RBIs.Walk-off this way: Angels blast off again
