The Blancos, taking 16 of 18 possible points, cruised to a first-place finish in Group B. The Danish side, with a meager four points, is out of European play for this season.
Luka Modric opened the scoring for the visitors with a strike in the 25th minute and Ronaldo made it 2-0 just three minutes into the second half.
The Portuguese international chalked up nine goals in the six matches of the group stage, a new record in the two-decade old competition featuring Europe's elite clubs.
Luka Modric opened the scoring for the visitors with a strike in the 25th minute
The identity of the second Group B squad to advance to the round of 16 won't be decided until Wednesday, when Juventus - at six points - and Galatasaray, with four, are scheduled to resume play in Istanbul after Tuesday's contest was suspended due to heavy snow.
Play was stopped at the 30-minute mark with the teams tied 0-0.
In Tuesday's other action, Bayer Leverkusen beat hapless Real Sociedad 1-0 to grab the second playoff berth from Group A over Shakhtar Donetsk, who lost 1-0 to group winner Manchester United.
Benfica edged Group C winner Paris Saint-Germain 2-1 to boost their point total to 10, the same as Olympiacos.
But the Greek side, victorious 3-1 over Anderlecht Tuesday, snagged second place on the strength of having defeated the Portuguese squad in head-to-head play.
Defending champion Bayern Munich retained the top spot in Group D despite losing 3-2 at home Tuesday to Manchester City.
While each team finished with 15 points, the German club took first place on goal differential.