2024-2025: Maiden Challenger title, top 200 Mejía received wildcards for the qualifying competition at the
2024 Los Cabos Open and also for the
2024 Abierto Mexicano Telcel in Acapulco. After coming through qualifying, Mejía won his first
Challenger singles title in the
2024 San Luis Open Challenger in
San Luis Potosí, Mexico, defeating fellow qualifier
Matías Soto in the final. He became the first Colombian Challenger champion since
Daniel Elahi Galán in 2022. He rose 100 spots back to world No. 344 in the singles rankings on 1 April 2024. Following a final showing at the
2024 Morelos Open also as a qualifier, defeating third seed
Zachary Svajda,
Dominik Palán, wildcard
Vasek Pospisil and sixth seed
Maxime Cressy, he returned to the top 300 on 15 April 2024. Ranked No. 235, Mejía entered the main draw of the
2024 Winston-Salem Open as a lucky loser but lost to
Corentin Moutet.
2026: Fourth Challenger title, top 150 Mejía won the fourth
Challenger, and the second of the same tournament in singles title in the
2026 San Luis Open Challenger in
San Luis Potosí, Mexico, defeating first seed and ranking n° 80 of the world
James Duckworth in the final. ==Performance timelines==