Ceci spent the 2019-20 season with the Toronto Maple Leafs, scoring one goal and adding seven assists in 57 games.
"Cody is a two-way defenceman who plays with size and a speed game that fits our system well," said Penguins general manager Jim Rutherford in a release. "He brings both regular season and playoff experience, and can be utilized on the penalty kill."
The 26-year-old played his first six NHL seasons with the Ottawa Senators. Over his career, the Ottawa native has scored 33 goals and registered 93 assists with a minus-53 rating in 496 games.
Ceci was originally selected by the Senators in the first round (15th overall) of the 2012 draft.
Pittsburgh finished third in the Metropolitan Division last year and was eliminated by the Montreal Canadiens in the Eastern Conference Stanley Cup Qualifiers.