Graham Fraser singled out Air Canada, which shares the top spot in the number of complaints filed against it in 2013-2014 along with the Canada Border Services Agency.
He told a news conference after he tabled his annual report that his office received 51 complaints about each of the two.
Next came National Defence with 31, Canada Post with 30 and the Canada Revenue Agency with 20.
Fraser expressed dismay that Air Canada (TSX:AC.B) did not seem to consider bilingualism a competitive advantage.
He also said he was mystified by Air Canada's attitude toward bilingualism, saying it's constantly reminded of ongoing investigations.
"Instead of looking at the question of offering services in the two official languages as a marketing asset, it appears to treat it as a burden," Fraser said.
Air Canada said it was surprised by Fraser's comments, adding that it takes its linguistic commitments very seriously.
"(We) regularly work with the official languages commissioner to improve our ability to serve our clients in the language of their choice," Isabelle Arthur said in an email.
Fraser also said problems exist with institutions that have direct contact with the public.
"We see that the use of the words 'Hello-Bonjour' are not part of the culture in the public service," he noted.
In Montreal, employees in many retail stores greet their customers with that phrase, indicating they can get served in either language.
But bilingual greetings are not enough to satisfy Yvon Godin, the New Democrats' official languages critic.
"For me, if it's a 'Hello-Bonjour, I don't speak French', that doesn't help me at all," he told a news conference.
Godin said that type of situation happens quite often at Air Canada's points of service.
"It's time to take action. . .Air Canada continues to violate the official languages law," he said, adding the airline should be hit with sanctions.
While Godin said the Harper government deserves "a big zero" in the official languages file, he also criticized Fraser's report as "lacking teeth."
Fraser promised to remain vigilant and said he is aware of the constant pressures that exist "in a world that is undergoing transformation in the world of information, communication and the way services are delivered."
The languages commissioner noted that other Montreal-based transportation companies, such as Via Rail, perform "in an exemplary manner."