In a sign of the times, the couple became the latest to spread their happy news via Twitter, with the duo posting matching pictures of themselves with a ring.
Northern Irish golfer and current world number six McIlroy told his more than 1.8 million followers: "Happy New Year everyone! I have a feeling it's going to be a great year!! My first victory of 2014 #shesaidyes!!"
Danish tennis player Wozniacki, who is also in her sport's top 10 according to latest rankings, also took to Twitter, saying: "Happy New Year everyone! Rory and I started 2014 with a bang! ... I said YES!!!!"