Ronaldo netted three times inside the opening 32 minutes to take his career total to 770 - three clear of Pele's tally of 767.
"Life is a solo flight. Each makes his own journey. And what a beautiful journey you are having. I admire you a lot, I love watching you play and this is no secret to anyone. Congratulations on breaking my record of goals in official matches," Pele posted on Instagram.
Some reports suggest this is a world record tally but that is disputed by the Czech Football Association, which claims former Austria and Czechoslovakia striker Josef Bican is football's true all-time top scorer with 821 goals.
Meanwhile, data from Rec.Sport.Soccer Statistics Foundation (RSSSF) says Bican scored 805 career goals. But among them were 27 goals for Rapid Vienna's reserve and amateur teams, as well as strikes which were not in official international games. Remove those and Bican finished his career on 759 goals - short of Pele and Ronaldo's total.
After the game against Cagliari, Ronaldo explained on Instagram why he is only now acknowledging the "record".
"The last few weeks were filled with news and stats considering me the world's top scorer in football history, overcoming Pele's 757 official goals," he said. "Although I'm thankful for that recognition, now it's time for me to explain why I didn't acknowledge that record until this moment.
"My ever-lasting and unconditional admiration for mister Edson Arantes do Nascimento [Pele], such as the respect that I have for mid-20th century football, led me to take into account his 767 score, assuming his nine goals for Sao Paulo State Team, as well as his single goal for the Brazilian Military Team, as official goals. The world has changed since then and football has changed as well, but this doesn't mean that we can just erase history according to our interests.
"Today, as I reach the 770th official goal in my professional career, my first words go straight to Pele. There's no player in the world who hasn't been raised listening to stories about his games, his goals and his achievements, and I'm no exception. And for that reason, I'm filled with joy and pride as I acknowledge the goal that puts me on top of the world's goalscoring list, overcoming Pele's record, something that I could never have dreamed of while growing up as a child from Madeira."
