The 34-year-old scored a penalty as Portugal lost 2-1.
His 700 goals so far have come from 973 matches - and he has scored at least once in 458 of those.
His goal in the 2-1 loss to Ukraine was also his 95th for Portugal, leaving only Iranian Ali Daei in front in the international charts on 109 goals.
The win for Ukraine, meanwhile, means they have qualified for Euro 2020.
Ronaldo's goal means he joins an elite group of players to have hit at least 700 goals in their career.
According to data from Rec.Sport.Soccer Statistics Foundation, Juventus forward Ronaldo is still some way behind the most prolific player of all time, with Czech-Austrian Josef Bican scoring 805 career goals.
Next on the list is Brazil legend Romario, who bagged 772, while his compatriot Pele is third on 767.
Hungary legend Ferenc Puskas hit 746 goals, while former Germany striker Gerd Muller rounds out the top five with 735 goals.