Bellinger played for the New York Yankees in 1999, 2000, and 2001. He played every position (including designated hitter) except for catcher and pitcher. Perhaps Bellinger's career high point came in the ninth inning of Game 2 of the 2000 World Series. Put in left field in place of David Justice, Bellinger's glove went over the wall to rob the Mets' Todd Zeile of a two run home run and preserve a crucial victory for the Yankees. The Yankees released him when he became eligible for arbitration; Bellinger then signed with the Anaheim Angels. He played two games at first base for the Anaheim Angels in 2002, had one at-bat in which he struck out, and was eventually demoted to the minor leagues.
While playing in the Baltimore Orioles system in 2004, he was recruited by owner Peter Angelos to play for the Greek baseball team in the 2004 Summer Olympics, held in Athens. Bellinger has Greek grandparents and Angelos was in charge of the Greek national baseball team. In order to field a competitive team in his hometown Olympics, Angelos made the controversial decision to use experienced American players mostly with distant Greek ancestry (players' ancestry eligibility was allowed to date as far back as great-grandparents), as opposed to native Greeks due to their inexperience in a country where baseball was almost never played. Bellinger reluctantly agreed as he hoped it would earn him a September call-up to the Orioles' roster when the Olympics were over. The Greek team went 1-6 and failed to advance to the medal round. Bellinger was clearly the most recognizable player from that team, one of a handful of players with Major League experience and the only player to have won a World Series ring. He was not promoted to the Orioles' roster after the games concluded.