The 24-year-old Cairns hails from the Wirral and is a talented footballer, having undergone trials with Liverpool as a youngster.
He leaves a Saracens side that booked its place in the Zurich Premiership Wildcard Final, despite being beaten 27-13 by Leeds in the second leg of their play-off clash at Headingley on Sunday.
Sharks coach Jim Mallinder expressed his delight with the signing of the young hooker, adding: "Matt is one of the most highly-rated young hookers in the Zurich Premiership and we are delighted he has agreed to join us."
Sharks, whose last match saw them go down by 34-19 to Saracens, narrowly missed out on the Zurich play-offs – involving the top three clubs – when they finished fourth, just below Northampton, who won just one more game than them in the 2002/03 season.
Cairns joins the club as they prepare for the move from Heywood Road to their new stadium, Edgeley Park, the home of Stockport County Football Club.
