His rep John Regna tells TMZ ... Jorge died of natural causes. Jorge is the youngest of 3 brothers and the second one, after Carlos, to pick up a guitar. Jorge was 14 when he started playing in San Francisco. He'd ultimately join a band in the '60s with some high school friends dubbed The Malibus.

The band's name later was changed in 1970 to Malo ... with help from the band's frontman's mother who'd scream at them "Todos ustedes son malo!" meaning they're awful.

Malo signed with Warner Bros and its self-titled album included the top 20 hit "Suavecito" ... known as the Chicano national anthem played at carne asada kickbacks all over the country. The track was such a huge hit ... Malo would end up performing on "American Bandstand," in 1972.

Malo would produce 3 more albums before breaking up. Jorge had also been playing in a band called The Fania All-Stars, which ended up playing at the classic Yankee Stadium in 1973 in front of more than 63,000 in attendance.

Five years later, Jorge released 2 solo albums titled "Jorge Santana" and in 1979 he dropped "It's all About Love."

He also worked with his famous brother with his management company as a director of artist relations. Jorge toured with Santana but in the '90s and they got together for the 1994 album "Santana Brothers" that included their cousin, Carlos Hernandez.

Not too long ago, Jorge appeared live occasionally with Malo and performed in front of a crowd that immediately reminisced to their high school days in the '70s thanks to "Suavecito."