Born in Apartadó, Antioquia Department, Mosquera started his career in the youth teams of Millonarios FC, finishing his development at Club Atlético River Plate in Argentina.
He returned to his country in July 2005 as he joined Unión Magdalena, where he played for half a year; while at the service of Millonarios, he became the youngest player to start a match in the Categoría Primera A at the age of 14.
Mosquera had a trial at Carl Zeiss Jena in summer 2007, but a heart attack made any eventual deal fall through.
[6] Having returned to Werder Bremen for 2007–08 – his league debut came on 3 November against Hansa Rostock[7] and his first top-flight goal against Energie Cottbus 21 days later, always as a late substitute[8]– he was loaned again in the 2008 January transfer window, to Alemannia Aachen in the second tier.
He helped his team narrowly escape top-tier relegation and, after his return to Werder, renewed his link and was loaned immediately, now to Union Berlin from Germany's 2.