Liddi was announced Monday along with 31 other players, as each Classic qualifier introduced two members of their squads as the tournament schedule was released.
Liddi, 24, will play with Team Italy as part of Pool D in Phoenix, which also includes Canada, Mexico and the United States. Games in Pool D will be played from March 7-10 at Salt River Fields and Chase Field.
Liddi competed for Italy in the 2009 Classic when he was a teenager who'd just completed his third season in the Mariners organization at the Class A level. He hit .375 (3-for-8) with a double and two RBIs in two games.
The first round of the tournament will be a round-robin format, with the top two teams at each venue advancing to one of two second-round pools in Tokyo and Miami. Winners and runners-up from each of the second-round pools move on to the Championship Round at AT&T Park in San Francisco from March 17-19.
Among the initial 32 players confirmed for the tournament, 12 are Major League All-Stars, including 2012 American League MVP Miguel Cabrera of the Tigers and World Series MVP Pablo Sandoval of the Giants, who will represent Venezuela.
Mariners pitcher Felix Hernandez is also expected to compete for Venezuela, but he was not announced on Monday.
Canada's first two announced players were first baseman Justin Morneau of the Twins and third baseman Brett Lawrie of the Blue Jays. Mariners outfielder Michael Saunders is expected to be extended an invitation from Canada.
Players who compete for their Classic teams will miss part of Spring Training, which begins Feb. 12 for the Mariners.