Being a kid, he mostly was interested in basketball not in baseball. He was inspired by Michael Jordan an even was involved in the Dominican Republic Junior National Basketball Team. He studied at the high school where his father worked and taught history. Nelson was a very talented person and additional to sport interest he also worked as a mechanics helper along with his uncle at a tractor factory as well as shined shoes and repaired them.

He started his professional baseball career in the early 2000s, when he joined the New York Mets team as a non-drafted free agent. In the 2000 he was traded to the Oakland Athletics team, where he played until 2004. In the 2004 he was traded to the Milwaukee Brewers instead of the infielder Keith Ginter. The next year he joined a new team “Milwaukee Brewers” and played there for a two seasons.

He made his first appearance in September 17, 2005 playing against the Houston Astros team. In the 2006 he signed a contract with the Texas Rangers team. He finally hit his first home run during the match against Willie Eyre team of the Twins.

During the 2007 season spring training he got off to a rough start, but later finished strong by hitting three home runs in the final week. In the 2009 he was selected as an All-Star at first time during his career as a replacement for injured Torii Hunter. Nelson along with Ian Kinsler became the first two teammates in the major league history to homer in each of the first three games in a season in the 2011.

In January of the 2013, Nelson became a part of a scandal because of drugs. Later he was suspended fifty games by Major League Baseball for that case. In the same year he became a free agent. In the 2014 he signed a one year deal with the Baltimore Orioles team for the $8 million dollars. In the same year, on December, he signed a new four-year contract with the Seattle Mariners.

During his career Nelson showed a good result in his stats. He was awarded with the Silver Slugger Award in the 2015 and reached the All-Star title four times, being a popular ESPN star. He is also very active in charity work. In the 2012 he help to buy a fire truck for Las Matas de Santa Cruz by donating 20 thousand dollars and two ambulances.

Nelson is married to Solani Genao. The couple tied their married knot on December 25, 2009. Nelson and his wife have two children, a daughter and a son named Giada and Nelson Jr. His net worth is approximately $32 million. He earns a lucrative amount of salary of 14 million dollars.