Mathis, 29, had spent the majority of his career with the Los Angeles Angels before being sent to Toronto in 2012. In his career he's batting .196/.256/.312, but he hasn't been in MLB for eight years for his bat.
Mathis has been key behind the plate for the Blue Jays this season ever since the injury suffered by J.P. Arencibia, maintaining a .997 fielding percentage to go along with an A.L.-leading 39 percent rate of throwing out potential base stealers.
With the signing, Toronto has opened the door for discussion about the starting job behind the dish in 2013.
Arencibia is batting .242/.279/.466 in 2012, but is currently on the disabled list recovering from a fractured hand.
Coming into 2012, d'Arnaud was the Jays' No. 1 prospect, and he hasn't disappointed, batting .333/.380/.595 for Triple-A Las Vegas. He was ranked 19th on MLB's preseason prospects list.
This offseason just got a little more interesting for Toronto, a team who is hoping to put together a championship caliber team in the very near future.