Born in Palmira, Valle del Cauca, Mendoza began his career at Envigado, making his debut in the Categoría Primera A on 8 August 2010, playing the full 90 minutes in a 0–1 home defeat to Atlético Huila. He made six appearances that season, and three in the following campaign, in addition to a further three in the 2011 Copa Colombia. After loans at América Cali and Cúcuta Deportivo, Mendoza signed a two-year contract at Deportivo Cali, the club who he supports, on 18 July 2013.
Chennaiyin FC
On 1 October 2014, Mendoza signed for Chennaiyin of the newly founded Indian Super League. He made his debut for the team, captaincy by Marco Materazzi, two weeks later in a 2–1 away win over FC Goa, replacing marquee playerElano for the final 23 minutes. On 28 October, he scored his first goals in the league, a first-half brace in a 5–1 rout of Mumbai City at the Jawaharlal Nehru Stadium. He added a third on 11 November, equalising for a 1–1 draw at FC Pune City, and a fourth eight days later in a 3–1 win over the same opponents. He finished the season with four goals from nine games as Chennaiyin won the regular season, but was absent through injury as they were eliminated in the semi-finals of the 2014 Indian Super League playoffs by Kerala Blasters.
On 31 August 2015, Mendoza was loaned back to Chennaiyin for the 2015 season. In their opening game, away to FC Goa, he scored a hat-trick in a 4–0 victory, and five days later he scored both goals in a win over Mumbai City. His sixth goal of the campaign came on 24 October, assisted by Elano in a 2–1 home triumph over Pune City. On 21 November, he recorded his second hat-trick of the campaign, in a 4–1 win over Kerala Blasters, and three days later he opened the scoring in a 4–0 home win over Delhi Dynamos with his tenth goal of the season. Menodza scored his eleventh of the season on 1 December, beginning a 3–0 win over Mumbai which ended their chances of the play-offs. On 12 December, in the first leg of the semi-finals, Mendoza concluded a 3–0 home win over reigning champions Atlético de Kolkata. In the final at Goa eight days later, he won two penalty kicks; Bruno Pelissari took the first, which was blocked by Laxmikant Kattimani but he scored the rebound, however Mendoza took the second and had it saved. Losing 1–2 with three minutes remaining, Mendoza scored an added-time winner as his team won 3–2. Mendoza was named the Hero of the League and also won the Golden Boot with 13 goals, two more than second-placed Iain Hume.
On 8 March 2016, Mendoza moved to the third continent of his career, signing a season-long loan at New York City FC of Major League Soccer. He made his debut five days later, playing the final 23 minutes in place of Tony Taylor in a 2–2 draw against Toronto FC at the Yankee Stadium. On 30 April, his eighth game, he scored his first goal for the team to decide a 3–2 home victory within five minutes of replacing Khiry Shelton. On 7 June 2017, Esporte Clube Bahia confirmed the loan of Mendoza for the duration of the 2017 Campeonato Brasileiro Série A. He scored 8 goals in 31 games as the Salvador-based club came 12th, including two in a 3–0 home win over Vasco da Gama on 20 August.
Amiens
On 17 January 2018, Mendoza moved to the fourth continent of his career, signing for Ligue 1 club Amiens until 2021. He made his debut that same day, starting in a 1–1 home draw with Montpellier HSC.
