López was born in Chile and began riding motorcycles at age four, encouraged by his father Renato López, a national motocross champion. His nickname "Chaleco" derives from the Spanish word for vest — specifically the protective vest worn in racing. From that early introduction to the sport, he built a career spanning motocross, supercross, enduro, and ultimately the ultra-demanding discipline of rally raid.
López broke into elite competition in 1989, winning the Latin American Motocross Championship in the 85cc class, which earned him an official Honda rider contract. Through the 1990s he dominated Chilean domestic championships: between 1990 and 1994 he contested the National Motocross Championship in the 125cc category, placing twice and winning twice; between 1995 and 2000 in the 250cc category he placed once and won five times. He also claimed the Latin American Supercross Championship in 1998.
In 2001 he became the first Chilean rider to earn a gold medal at the Six Days of France (ISDE) at Brive-la-Gaillarde. He followed this with international enduro results — eighth in the 250cc four-stroke world championship in Finland in 2002, and tenth in the 500cc four-stroke category at the same event in 2003. A gold medal at the 2003 Six Days of Brazil in Fortaleza saw Chilean sports journalists name him rider of the year.
López made his Dakar debut in 2007 but was forced to retire during the race. The 2008 Dakar Rally was cancelled as a competition and replaced by the 2008 Central Europe Rally, in which he finished second. Returning to Dakar in 2009, he won the first stage and finished seventh overall, and the same year placed third in the Tunisia Rally.
His 2010 Dakar campaign was his most prominent motorcycle result: he won the fifth, eighth, and twelfth stages, claimed first in the 450cc sub-category, and finished third overall. That third-place overall finish, shared in Chilean record-books with compatriot Carlo de Gavardo (2001 Dakar), remained the highest overall placing achieved by a Latin American rider at the Dakar Rally at the time.
López subsequently transitioned into four-wheeled off-road competition in the UTV/SSV and Lightweight Prototype (T3) categories. He won the Dakar's T4 (UTV/SSV) class in 2019 and 2021, and the T3 (Lightweight Prototype) class in 2022, demonstrating versatility across different machinery and regulations.
When the FIA World Rally-Raid Championship launched its inaugural season in 2022, López entered in the T3 category and claimed the title, adding a world championship to his Dakar victories. The championship unified the leading cross-country rally events under a single FIA points structure, giving his 2022 season win global recognition beyond the Dakar alone.
Before committing fully to Dakar, López competed extensively in South American and European rally raids. He won the 450cc category at the Patagonia-Atacama Rally in 2006, placed second in the d'Italia Sardegna Rally in Italy, and finished second in the 450cc class at the Morocco Rally. Earlier he had contested the Patagonia-Atacama Rally in 2005, winning the fourth stage before a mechanical failure forced his retirement, though he still managed fourth overall.
López is considered a pioneer of Chilean motorsport in the off-road discipline. His 2010 Dakar third-place result stood as the highest Latin American finish at that race at the time of its achievement. Across motorcycle and car categories, his three Dakar class wins spanning 2019, 2021, and 2022 mark him as one of the most consistent performers in rally raid's alternative-vehicle classes. His career arc — from junior motocross champion to world rally-raid champion — reflects both individual skill and the growth of Latin American presence in international off-road racing.