The club confirmed the deal on Thursday, saying the eight-time Ballon d'Or winner's involvement would drive both sporting and institutional growth.
"Leo Messi's arrival marks the beginning of a new chapter in the club's history, aimed at driving both sporting and institutional growth, strengthening its foundations, and continuing to invest in talent," the club said.
"The project is guided by a long-term vision and a strategic plan that combines ambition, sustainability, and a strong connection to its local roots."
Messi moved to Barcelona from Argentina at the age of 13 and made his first-team debut for the Catalan giants in October 2004 at the age of 17. He went on to score a club-record 672 goals in 778 appearances, winning four Champions League titles and 10 La Liga titles before leaving for Paris Saint-Germain in 2021. He has been at Inter Miami in MLS since 2023.
Cornella, founded in 1951, play in the Tercera RFEF and are currently in the playoff positions as they aim to return to the fourth tier. Their small stadium holds around 1,500 spectators, but the club has a strong youth development history — Arsenal goalkeeper David Raya and former Barcelona and Inter Miami defender Jordi Alba both came through its ranks.
Messi's purchase follows a trend of footballing icons moving into club ownership. Cristiano Ronaldo bought a 25 per cent stake in Spanish side Almeria in February.