But asked by the Evening Standard whether she would stand, she said: "Absolutely not. I am a proud Londoner.
“And I could assure you if I was the Mayor of London, nobody would get a minute of peace.
"But I would never stand to be the Mayor of London while I have a full-time job."
A shortlist of candidates is set to be compiled by Conservative Party Headquarters this week followed by a series hustings. A final candidate will be announced in July.
Baroness Brady refused to back any of the Tory contenders who have declared they want to run against Mr Khan, who will be fighting for a historic third term at the election next May.
"I haven’t been following the race that closely," she added.
She was speaking ahead of the launch of new research from Simply Business, which found the number of small business owners reporting mental health difficulties had more than doubled in the past year.
Baroness Brady, an ambassador for the company, said the economic climate is only getting tougher for aspiring entrepreneurs and small business owners.
“Everything is more expensive,” she said. “Rent is more expensive, getting a coffee is more expensive, paying staff is more expensive.
“But it’s everything: Congestion charges, Ulez— everything.”
But while a run for mayor isn’t in Brady’s sights, she did have some thoughts about what local governments can do to help entrepreneurs.
“Local councils can organise facility hubs where people can share ideas, and they can also help with free advertising to help people to shop local,” she said.
TV judge Rob Rinder was another celebrity touted as a potential Mayor of London candidate, however he has distanced himself from the reports.
London Assembly members Andrew Boff and Susan Hall have said they will stand.
Samuel Kasumu, a former Downing Street aide to Boris Johnson, tech entrepreneur Daniel Korski, ex councillor Duwayne Brooks, former aide to the Royal family Natalie Campbell and businessman Alex Challoner have also entered the race.
London Minister Paul Scully was arguably the first political “big hitter” to enter the race. The Sutton and Cheam MP dismissed suggestions he was not well enough known to defeat Mr Khan, whose victories in 2016 and 2021 came with record majorities.
“This isn’t a celebrity election,” Mr Scully told the Standard.
“Celebrity status doesn’t get houses built, doesn’t get transport moving, doesn’t make people safe. That is what I’m focusing on.”