The Dublin comedian's show beat the likes of Strictly Come Dancing (second place), EastEnders (fourth place) and Coronation Street (seventh place) to the top spot with a staggering 6.8 million viewers.
6.5 million tuned in for Strictly Come Dancing's festive episode, while 6.3 million turned in to watch EastEnder's Christmas Day special. Strictly Come Dancing had enjoyed a 7.2 rating the previous year.
In third place was 'Call The midwife', BBC1, with 6.3 million The only other broadcast to get a higher rating than Mrs Brown's Boys was the Queen's speech with a total of 7.6 million viewers on both the BBC and UTV. The BBC attracted 5.9 million viewers for the Queen's Christmas Broadcast, while ITV pulled in an additional 1.6 million for it.
Doctor Who, which featured a female doctor in Jodie Whittaker for the first time ever, was the sixth most watched show with 5.7 million for BBC1.
ITV's Coronation Street was seventh with 4.8 million viewers. But this figure excludes plus-one. It was followed by the BBC News, which came in in at eight place with 4.2 million viewers.
In ninth place was the BBC 1s The Highway Rat with 4 million viewers. Finally, ITV's Emmerdale squeezed into the top 10 with 3.5 million, rising to 3.7 million with plus-one
Director of BBC content, Charlotte Moore, said: "Millions of people chose BBC1 on Christmas Day and came together to enjoy the top six most popular programmes from comedy, drama and entertainment, with Mrs Brown's Boys returning to the top spot."
In the latest episode of Mrs Brown's Boys, the new Rory was revealed, with the actor Damien McKiernan taking over the role.
Meanwhile, we reported earlier in the week that the the Dublin comedian has revealed that he is hoping that the likes of The Script and Picture This will pen songs for a new musical show he is planning to stage in 2019.
Revealing that he's hoping to get some big Irish acts involved, Brendan says: "The Script, I’m hoping, will do a number. Picture This will do one. I haven’t written the story yet, but that’s where we are heading.
"We are very lucky because everybody sings. Some of them have amazing voices, and then there will be a couple of them who will rap. It will be fun.
The new musical will tour Ireland, the UK, Australia and New Zealand in 2019.
"I’m writing a new show for 2019, Mrs Brown: The Musical. It will still tour, I wouldn’t stay in one place," Brendan told the Evening Herald.
"One of the reasons why I haven’t done Broadway or London is because they want you to stay in one place for six months. That’s like a real f***ing job."
"Everyone will be singing. It’s hard writing anything. I’ve written a few songs. It won’t be just me."