The five-time Ballon d'Or winner converted a penalty in the 72nd minute after a Ukraine player was judged to have handled a long-range shot in the box.
"Records come naturally, I don't look for them, records are looking for me," Ronaldo said after the match.
"Without having this obsession, they happen naturally. It's a beautiful moment in my career but it turns out to be bitter because we didn't win. But in my opinion we have to be proud because we played an excellent game. Why did I look to the sky in the goal? It's not a number that everyone can reach. I thank you all, teammates, colleagues, coaches who have helped Cristiano to be the player he is, but there is a bitter taste for not winning."
Ronaldo is the sixth player to achieve the feat, following ex-Germany striker Gerd Muller, Hungary legend Ferenc Puskas, Brazil's Pele and Romario, and the Czech Republic's Josef Bican.
The only other active player close to breaching the 700-goal mark is Barcelona and Argentina star Lionel Messi, who has 672.
Ronaldo, 34, made his international debut at the age of 18 in a 1-0 victory over Kazakhstan on Aug. 20, 2003, and scored his first goal in the opening match of Euro 2004, which Portugal lost 2-1 to eventual winners Greece on June 12, 2004.
At club level, Ronaldo scored five goals for Sporting, 118 with Manchester United, a club-record 450 with Real Madrid and 32 for his current side Juventus.
At international level, Ronaldo's tally of 95 goals is second only to Ali Daei's 109 for Iran.
"I am proud of the team. How many records do I have? I don't know. I just want to enjoy the moment and football, everything I've been achieving. Thanks to all who helped me reach this impressive milestone," Ronaldo added after his side's defeat to Ukraine.
Some outlets reported Ronaldo reaching the 700-goal milestone on Friday after his goal in Portugal's 3-0 win over Luxembourg. The difference was a goal against Real Sociedad in 2011, which Real Madrid teammate Pepe said belonged to his fellow Portugal international to help out in a tight Pichichi race against Barcelona's Lionel Messi for the league's top scorer that year.
However, most statisticians -- including ESPN's Stats & Information -- do not credit Ronaldo with that goal.
ESPN FC's Spain correspondent Adriana Garcia contributed to this report.