Romeo, one of Beckham's five children with wife and fashion designer Victoria, played for American third-tier club Fort Lauderdale in their 2-2 draw with South Georgia Tormenta on Sunday.
Fort Lauderdale is the reserve team of Inter Miami, the Major League Soccer club co-owned by Beckham.
"Blessed to have made my pro debut," Romeo said in a post on Instagram with a photo of himself in the number 11 jersey. "Full focus on to the next match."
The teenaged midfielder played alongside Harvey Neville, the son of Inter Miami head coach Phil Neville. Neville and Beckham were team mates at Premier League club Manchester United.