Born in Madrid, Montero made his senior debuts with local AD Villaviciosa de Odón in the 2008–09 season. In the 2009 summer he joined AD Alcorcón B also in the lower leagues, but returned to former club in 2010.
In July 2011 Montero moved to another reserve team, Real Zaragoza B in Segunda División B. After being sparingly used during the season, he joined fellow third-divisioner RSD Alcalá in July of the following year.
On 3 August 2013 Montero moved to Zamora CF, also in the third tier. After scoring nine times in 19 matches, he joined Real Jaén. On 23 February 2014 Montero played his first match as a professional, starting in a 0–0 away draw against Córdoba CF for the Segunda División championship.
