Barrowman and comedian Karen Dunbar performed a song called Welcome to Scotland during the opening ceremony for the 20th Commonwealth Games.
The routine took viewers on a trip around Scotland and included landmarks such as Gretna Green, the Forth Rail Bridge and Nessie.
However, viewers criticised his performance on social media, describing it as "bad" and a "reason to vote Yes in the independence referendum".
The Glaswegian actor has now hit back at his critics. After retweeting some of their negative comments, he tweeted: "I am retweeting the negative because I want you all to see how bitter and nasty and negative some people are:) I am so happy right now.
"I don't care...
"I'm Scottish and you can never take that away no matter what your politics are. Bitterness makes you ugly and old very fast:) happy jb."
Within seconds of Barrowman appearing on the pitch at Celtic Park, the world of Scotland's social media was divided even more than usual.
Kieran Caw, a prominent football tweeter, set the tone and generated hundreds of retweets within seconds with the pithy: "Worst start at Celtic Park since Efe Ambrose's nightmare vs Juve last season."
Irish Glasgow-based journalist Peter Geoghegan added: "This is possibly the most kitschy thing I've ever seen. And I'm from a country that revered the Eurovision."
Glasgow University academic David Archibald said: "There are Scottish people the world over tuning into the #Games2014 opening ceremony and not feeling homesick."
Screenwriter Simon Ricketts tweeted: "Positivity, smiles, silliness, passion, fun, identity yet inclusiveness, music, charity. Yes, I can see why you hate it."
But amid the expected flurry on Scottish independence, the politics of sexuality took centre stage with Barrowman kissing a male dancer, a clear reference to anti-gay laws in many Commonwealth nations.
Amnesty International tweeted: "A big kiss goes out to the 42 of 53 Commonwealth countries where it is a crime to be gay."
Tom French of the Equality Network, added: "42 of 53 Commonwealth countries criminalise same-sex relationships - that's why this kiss was important."
Scotland's controversial team outfit came in for comment, with Margot McCuaig tweeting: "I'm actually looking forward to seeing how the Team Scotland outfits sit alongside the wee dug. They may just rock it."