Lenny Castro is a percussionist of Puerto Rican descent and was born and raised in New York City. His father, Hector Castro, played the keyboard in a Latin style and gave Lenny his first pair of congas when he was five years old. Along with the congas Lenny played the bongos, which he grew up performing on the streets. Unlike many of his "Latin brothers", Castro listened and played percussion not to just Latin music but jazz, rock, classical, and anything else that could have percussion added in. Lenny claims not to have planned on becoming a studio musician, only that he wanted to play music. Whether this meant live or in recordings, he didn't care as long as he got to play. He later began to make money with different gigs in New York, which he called a "playground" at the time, when he was around 14 or 15. This lasted him until he graduated from high school in 1974. After graduation he went to Mannes college with a scholarship that a high school teacher had helped him to acquire. However, he tired of college quickly and dropped out. He found a job at a famous drum shop in New York where he worked for three or four months.
It was through this store that he got a big break with Melissa Manchester who had a hit at the time, "Midnight Blue". After Castro did a couple of tours with her, Melissa moved to Los Angeles. Lenny, 19 at the time, did not want to give up this opportunity and left New York City to follow Melissa and his career. Her producer later introduced Castro to fellow producer Richard Perry. Perry then had Lenny play at a Diana Ross session, which is where he met Jeff Porcaro. Porcaro got Castro a gig with Boz Scaggs, who had just released an album called "Silk Degrees". Boz toured all around the world with Lenny as their percussionist. This huge tour is what landed Castro the Toto gig and also kick-started his Los Angeles session legacy.
The artists and bands that Castro has worked with include Al Jarreau, Boz Scaggs, Toto, Mars Volta, Dolly Parton, Diana Ross, Stevie Wonder, David Sanborn, Little Feat, Boney James, Peter White, Joe Sample, Kenny Loggins, Ricky Lee Jones, Dan Fogelberg, The Crusaders, Barbra Streisand, Simply Red, Karizma, Quincy Jones, Randy Newman, Dave Koz, Olivia Newton-John, the Red Hot Chili Peppers, Oasis, Wayne Shorter, Pat Benatar, and Dwight Yoakam.