The 16-year-old forward came off the bench in the 73rd minute at Portugal's Cidade do Futebol training complex in Oeiras, entering the match with his country already in control of their European Under-17 Championship qualifying fixture.
His appearance attracted considerable attention, with several members of Portugal's senior squad watching from the stands. Vitinha, JoĂŁo Neves, JoĂŁo FĂ©lix and JoĂŁo Cancelo were among those present as the teenager made his first appearance at this level.
Ronaldo Jr. is developing in the youth ranks at Al Nassr, where his physical attributes and goalscoring instincts have helped him attract attention. Standing around 1.90 metres tall, he already has a significant presence for a player of his age.
He was deployed in an advanced position against Andorra, operating close to the opposition penalty area and looking to use his height and movement to trouble the defence.
Although he did not find the net, he came close to marking his debut with a goal. A cross from the left found him in the penalty area, where he got his head to the ball, but his effort drifted narrowly wide of the post.
Portugal had already established their advantage by the time he entered the contest. Diego Farinha opened the scoring with a free-kick before KauĂŁ Miranda converted a penalty after the interval. Rafael Cabral added a third, and Farinha completed his brace to seal the 4-0 result.
The match was part of Portugal's qualifying campaign for the 2027 European Under-17 Championship, giving Ronaldo Jr. the opportunity to make his first appearance in a competitive fixture for the age group.
His next opportunity could come against Bulgaria, where he will hope to build on the minutes he received against Andorra and strengthen his position within the squad.
The attention surrounding the teenager is inevitable given his father's standing in Portuguese football, but his immediate task is to establish himself on his own merits. His debut provided an early glimpse of his physical strengths and movement in the penalty area, even if the search for his first under-17 international goal continues.