Sun News Network went off the air at 5 a.m. ET Friday after failing to find a new owner.
Programming on the channel was replaced with a Sun TV logo.
Sun Media Corp. issued a statement saying it spent months unsuccessfully trying to find a buyer, but financial losses meant it could not continue to operate.
"This is an unfortunate outcome; shutting down Sun News was certainly not our goal," said Julie Tremblay, President and CEO of Media Group and Sun Media Corporation.
"Over the past four years, we tried everything we could to achieve sufficient market penetration to generate the profits needed to operate a national news channel. Sadly, the numerous obstacles to carriage that we encountered spelled the end of this venture," Tremblay said in a statement
The network's website featured only a Sun News logo on Friday morning.
- Quebecor sells 175 Sun Media newspapers and websites to Postmedia
- Ezra Levant, Sun News Network host, ordered to pay $80,000 in libel case
- Justin Trudeau gets apology from Sun Media
The network began broadcasting in April 2011, launching a right-of-centre programming schedule, but it has had a constant challenge attracting viewers.
Its supporters blamed the CRTC for not giving it the same access enjoyed by news channels operated by CBC and CTV.
The federal broadcast regulator denied Sun News a guaranteed spot on basic cable TV packages in August 2013.
Data released as part of that application showed that while the network was available to 5.1 million households, it was only attracting, on average, 8,000 viewers at any given time.
That number was far lower than what well-established all-news networks operated by CTV and CBC were reporting. CBC, for example, said it had eight times as many viewers as Sun News.
Hosts courted controversy
When Quebecor launched the station, media pundits quickly dubbed it "Fox News North."
On the first day of broadcasting, Ezra Levant, one of the most controversial hosts of Sun News, showed the Danish cartoons of the Prophet Muhammad to TV viewers.
According to a Canadian Press report, Levant said he's grateful for the freedom he had at Sun News, and while he doesn't know what he'll do next, he still has "a lot of things to say."
"I still have a point of view that some people like, some people don't like, but I think it has its place in the spectrum of opinion," said Levant, noting he was "overwhelmed" by feedback from fans.
"I think that people had a passionate response to the Sun, pro or con, that they didn't feel for all news channels."
When Postmedia announced last October that it was buying Quebecor's Sun Media Corp. and its 175 English-language newspapers — including the Toronto Sun — the TV channel was not included in the deal.
The network employs about 200 people.