Bernadina was signed at age 17 by the then-Montreal Expos as a nondrafted free agent in 2001. He beat out Todd Liebman for the last roster spot on the Dutch national team for the World Baseball Classic back in June 2012. Bernadina was called up to the major leagues the first time on June 28, 2008, to replace the injured Lastings Milledge. His major league debut came the next day, and he hit a single to right field in his first major league at bat. Bernadina started 2009 in the minors, but was called up on April 15. After appearing in two games, he made his first start of the season on April 18. In the eighth inning, he "made a spectacular catch against the wall" against the Florida Marlins and fractured his right ankle, although he earned the nickname "The Shark". On May 12, 2010, Bernadina hit his first and second big league home runs against the New York Mets. The second came in the ninth inning off Francisco Rodriguez, giving the Nationals the lead in a game they would ultimately win. He also made a remarkable leaping catch in right field that likely robbed Met Jeff Francoeur of a bases-clearing triple. 2012 was Bernadina’s best year in the majors. He compiled a slash line of.291/.372/.405 and made a spectacular game-saving catch against the wall at Minute Maid Park. On August 19, 2013, Bernadina was released to make room on the roster for David DeJesus, who was acquired from the Chicago Cubs.
Philadelphia Phillies
Two days after being released by the Nationals, Bernadina signed with the Philadelphia Phillies. He appeared in 27 games for them and hit.187. He was outrighted off the roster on October 16, 2013.
Cincinnati Reds
On January 31, 2014, Bernadina signed a minor league contract with the Cincinnati Reds that contained a spring training invitation. After making the opening day roster, he was designated for assignment on May 3, but was called back up after an injury to Jay Bruce. Bernadina was designated for assignment again on June 21, 2014 On June 27, Bernadina was released and became a free agent. He hit only.153 in 44 games for the Reds.
On July 7, 2014, Bernadina inked a minor league deal with the Los Angeles Dodgers. He was assigned to the Triple-A Albuquerque Isotopes, where he hit.246 in 23 games. He was called up to the Dodgers on September 6, 2014. He was used primarily as a pinch runner for the Dodgers but also had 7 at-bats as a pinch hitter. He had two hits, one of which was a home run.
On November 24, 2016, Bernadina signed with the Kia Tigers of the KBO League. He had a.320 batting average, 27 home runs, 111 RBIs, and 32 stolen bases in the 2017 KBO League season. On December 1, 2017, Bernadina signed a one-year, $1.1 million contract with the Tigers. His 2018 statistics included a.310 batting average, 20 home runs, and 70 RBI. He became a free agent after the 2018 season.
On April 18, 2019, Bernadina left the Million Stars to sign with the Lamigo Monkeys of the Chinese Professional Baseball League. He posted a.256/.365/.378 slash line across 24 games before he was released by the team on June 30, 2019.