The second year of the deal is a team option, according to a source.
The Sporting News reported the total value of the deal is $9 million.
Clark leaves the Los Angeles Lakers, who have been in a holding pattern with free agents as they wait for a decision from Dwight Howard, after averaging career highs in points (7.3) and rebounds (5.5) last season.
Though the 6-foot-10 Clark has typically played power forward during his career, the Cavs see him as a defender with length who can guard some opposing small forwards. The Cavs recently drafted Anthony Bennett with the No. 1 overall pick and have slated him to play power forward with resident starter Tristan Thompson.
The Cavs entered free agency with more than $22 million in salary-cap space and are expected to continue to be active in free agency and the trade market as they look for a small forward and a backup point guard.