Cape Town fire and rescue services spokesperson Jermaine Carelse said no one was injured in the blaze.
“The fire started about 3am. The building on the outside of the property was badly damaged,” he said. “It was extinguished by 4.30am.”
The cause of the fire is unclear. Dean Kadir, who has owned the pub for more than 30 years, said assessors were investigating.
“By the look of it, it is electrical,” he said. “Our beer garden is completely gone. The inside, fortunately, only received smoke damage. The inside is where you find the historical value.”
He said the show would go on and that “hopefully, one of the bars will be up and running” by the weekend.
He added that stalwarts Sesame and Babelas, two cats often found sleeping at the pub, were safe.
Many took to social media to convey their dismay at the news.
“Fireman's Arms burnt down in the early hours of this morning. That's some sick irony. RIP to a great bar,” said Twitter user Garth Manthe.