Blaithnaid beamed as she was spotted on Dublin's South William Street, looking cool and casual in a chic black leather jacket which provided the perfect backddrop to her elegant new diamond.
The RTE star, 29, gave fans a glimpse of her sophisticated emerald cut diamond ring - which sits on a pretty yellow gold band - when she announced her big news on Instagram at the beginning of the month.
"Mexico really was a trip we will never forget," the host of Dancing With The Stars spin-off show, Can't Stop Dancing, said on her announcement.
"So great to be home and celebrate with friends," she added, alongside photos of herself and her fiancé, and a close-up of her elegant engagement ring.
Other Dancing With the Stars cast members Aoibhin Garrihy and Erin McGregor were among those wishing the newly-engaged couple well, as well as model and former Xposé host Ruth O'Neill.
The couple spent a month in Mexico, which began with them both celebrating Blathnaid's brother Fiachra's wedding before taking off together to see all that the country has to offer.
One of the first ports of call for the couple was La Casa Azul in Mexico City, which was the home of famed portrait artist Frida Kahlo.
Blathnaid and her musician boyfriend also visited Tulum on their travels, taking in an ancient Mayan city as well as the white, sandy shores of the Mexican coastline.