Romeo, 19, starred in the second string's 2-1 victory over Rochester New York FC and was cheered on by his brother's Brooklyn,23, and Cruz, 17.
Romeo has his eye set on breaking into Phil Neville's first team squad by next year and did his chances no harm following his display in the victory.
The forward produced a mature piece of play when, rather than shooting, he played in team-mate Shanyder Borgelin to fire home the crucial goal.
George Acosta had broken the deadlock early in the second half for Inter Miami before Doncaster Rovers loan signing, Englishman Ed Williams, levelled up for Rochester late on.
But it was Inter Miami who had the final say thanks in part to some superb play from Romeo.
Following the win, Beckham Sr entered the pitch to give his son a hug after his part in the match-winning goal.
Beaming with pride, the former Manchester United star then took to social media posting: "Fun night tonight with the boys @romeobeckham @cruzbeckham watching the team win an important game @intermiamicf"
Dressed in the club's pink training top and cap, the former England captain appears to be relishing his time as president and co-owner of the Florida-based club.
But it looks as though he will be pinning his hopes on Romeo to follow in his footsteps after Brooklyn and Cruz opted for careers away from football.
Brooklyn has made a living as a chef, whilst Cruz is a social media star but both were delighted for their brother following his exploits.
Boss Phil Neville came in for criticism in July when he fielded Romeo and his own son Harvey in a 6-0 friendly defeat to Barcelona with many feeling they weren't deserving of an appearance against such prestigious opponents.
But Romeo might not have to wait too long to earn his first-team spot on merit if he continues his excellent form.