He had had several chances as his side came from behind to win thanks to an own goal and Francisco Conceicao's stoppage-time clincher.
Ronaldo, 39, already has the record for most Euro games (26), goals (14) and goals at five editions of the tournament, said German news agency (dpa).
It was a big couple of days for the Ronaldo family, with his eldest son Cristiano Jr celebrating his 14th birthday.
But an Instagram video from Ronaldo's partner Georgina Rodriguez showed his son was in Germany's pink away kit and not in Portugal colours as he opened presents.
Ronaldo's team mate Pepe also became the oldest men's player at a Euros after starting against the Czechs.
The defender, at 41 years and 113 days old, beats the previous record holder Gabor Kiraly of Hungary by over a year.
"Everyone knows how hard I've worked to be here today. It was a difficult game, we didn't deserve to concede that goal. The team was extraordinary and was always in control," Pepe told reporters.
-- BERNAMA
