Sanchez had been in a coma since Feb. 14, when he was struck in the head by a motorboat's propeller while he was swimming in Campano, Venezuela, his home country.
He played for the Caracas Lions, which released a statement Saturday night announcing his death.
Sanchez signed with Seattle as an international free agent in 2011, when he was 16. He had been scheduled to join the organization's minor league mini-camp in Arizona, according to ESPN.
"The Seattle Mariners are saddened to learn of the passing of Victor Sanchez," Mariners Executive Vice President and GM Jack Zduriencik said in a statement, as reported by ESPN. "Victor was a tremendous young man and a wonderful teammate. He was a very talented player who was close to fulfilling his promise as a major leaguer. He will be missed by his teammates and the coaches and staff at the Mariners. The entire Mariners organization sends our deepest condolences to his family during this difficult time."