LeBron cheered and clapped for him -- and chanted "MVP" -- as he waved from his VIP area

The Los Angeles Lakers star entertained the roaring crowd at the Puerto Rican-born superstar's concert in San Juan Friday night ... hopping on stage as he got down to the music.

LeBron, decked out in blue joggers, a floral-print button down and a yellow bucket hat, seriously looked like he was having the time of his life as he vibed to "Titi me preguntó" and recorded the experience. He hasn't posted any footage he shot on his phone yet ... but he clearly took home some serious memories.