The contract is worth $750,000 in the NHL and $250,000 at the AHL level.
Jaros, 24, appeared in 13 games for the Senators last season, recording three assists and six penalty minutes. In 34 contests with the AHL's Belleville Senators, Jaros scored two goals and 15 points.
“Despite being limited by injury last season, Christian proved to be a reliable defensive defenceman,” Senators general manager Pierre Dorion said in a statement. “He’s a big body who’s rangy and who skates well. With his considerable professional experience, we’ll look for him to challenge for a roster spot in Ottawa when camp begins.”
A fifth-round pick of the Senators in 2015, the Kosice, Slovakia native has a goal and 13 points in 76 career NHL games with Ottawa.