In 2010, Tesillo moved to Categoría Primera A side Deportes Quindío, along with three other Centauros teammates.[3] He made his debut in the category on 4 April, starting in a 0–1 away loss against Boyacá Chicó.
Tesillo scored his first goal in the top tier on 8 May 2011, netting his team's third in a 4–3 home success over Deportivo Pereira.[4] An undisputed starter for the club, and left with 134 official appearances.
Junior
On 19 December 2013, Tesillo signed a one-year loan deal with fellow top-tier club Junior.[5] He made his debut for the club the following 25 January, coming on as a late substitute for Luis Enrique Quiñones in a 3–2 win at Atlético Huila.[6]
Tesillo became an undisputed starter at the club, and had his loan extended for a further year in December 2014. He left the club after his loan expired, and the club opted to not activate his buyout clause.
Santa Fe
On 29 December 2015, Tesillo signed a three-year contract with Independiente Santa Fe.[7] He made his debut for the club on 31 January of the following year by playing the full 90 minutes in a 1–0 win at Boyacá Chicó.[8]
Immediately a first-choice, Tesillo scored his first goal on 21 February 2016, but in a 1–2 away loss against Envigado.[9] He contributed with a career-best four goals in 36 appearances.
Tesillo appeared in all four matches during the tournament, as his side was knocked out by eventual champions Brazil in the quarterfinals.
In May 2018, he was named in Colombia's preliminary 35 man squad for the 2018 World Cup in Russia.[12] However, he did not make the final cut to 23.[13] On June 28, 2019, his missed penalty kick in the shootout, saw Colombia eliminated by Chile in the 2019 Copa America quarterfinals.
↑"Noticias equipos Torneo Postobon"[News about Torneo Postobon teams] (in Spanish). Torneo Postobon (página no oficial). 22 January 2010. Archived from the original on 20 December 2016. Retrieved 17 December 2016. Cinco jugadores importantes salieron del equipo profesional, que este año será dirigido por Eduardo Cruz. Se trata de William Tesillos, John Jairo Roy, Julián Rosero, el argentino Alexis Bravo (todos al Deportes Quindío) y Jair Valoy, quien fue al Cortuluá. Por el momento no se conoce acerca de refuerzos.
