Nicknamed Manotas, Mejia made his professional debut playing with Tauro in 2007.
In 2008, he was transferred to Uruguayan side Centro Atlético Fénix, but finally made his team debut on 21 August 2010 on a match against Tacuarembó, being rewarded as the man of the match.[1] His outstanding performances called the interest of various team of Europe.
In January 2011, he was loaned 6 months to Toulouse but was never able to win a place in the first team, so he had to cope with playing in the reserve team.[2]
Upon his return to Fénix, he moved to playing in the starting lineup of the team.