Ronaldo was pictured in tears as he left the field in the aftermath of Portugal's 1-0 defeat to Morocco in the quarterfinals.
It remained to be seen whether the 38-year-old would ever return to add to his 196 caps and 118 goals.
Fernando Santos has since paved way for Roberto Martinez as Portugal's new manager, and the Spaniard has called upon the five-time Ballon D'or winner.
Ronaldo now plays in Saudi Arabia for Al Nassr, where he has scored nine goals in his first 10 games for his new club.
The former Manchester United, Real Madrid and Juventus forward will become the most capped men's footballer of all time if he plays in Portugal's EURO 2024 qualifier against Liechtenstein later on Thursday.
"I'm not going to lie. In our life, we have to put everything on the scale," Ronaldo said ahead of a the game.
"We thought, we reflected, me and my family, but then we came to the conclusion that, despite the difficulties, we cannot throw in the towel. I was able to see situations at different angles. I learned a lot from that.
"I'm glad to be back. Roberto Martinez showed that he counted on me. I've always wanted to play. As you know, he talked to everyone and to me, too. And I was able to realise that I have a lot to give to the national team.
"I feel it, I want it, and my desire is to take Portugal to the highest level. I will always give my contribution when they need me."
Ronaldo captained Portugal to the European Championship title in 2016 and the inaugural UEFA Nations League trophy in 2019.
