A Tory leadership contest is the "last thing" the country needs, he said. Ms Widdecombe noted that as the UK recovers from the pandemic, the focus should be on the NHS and the economy.
Added the former Tory MP: "I don't think he's done yet.
"We don't need the uncertainty of a leadership election now.
"We need to fix the economy and the NHS waiting lists.
"You don't need months of uncertainty because you don't know who will be PM. It's absurd.
"He's done it, and it's being investigated.
"He would have lost popularity anyway. Now let's get the country back on track.
"I think we all need to grow up and stop thinking that every crisis necessitates a new leader.
"Stop obsessing about Boris and start caring about NHS waiting lists, the economy, and the pandemic's end.
"These are the concerns we should have. I'm not sure why people focus on personalities."
Ms Widdecombe's remarks come after the Prime Minister apologised for attending a "bring your own booze" gathering in No 10's garden during the initial lockdown.
He said it was a "business event" during a tense Prime Minister's Questions.
The Commons was packed as Mr Johnson gave his first public response to the leaked email encouraging staff to "bring your own booze" to the May 2020 event.
The PM said he came out for about 25 minutes to "thank groups of personnel" but "should have sent everyone back inside".
To the public's indignation, Mr Johnson admitted, "I know they feel towards me and the Government I head when they think the rules are not being properly obeyed by those who write the rules."
"There were things we simply did not get right, and I must accept responsibility," he admitted.
Sir Keir Starmer, Ian Blackford of the SNP and Sir Ed Davey of the Liberal Democrats all called on the Prime Minister to step down.
Mr Johnson's position was "no longer tenable," said STV's Douglas Ross.
Former Tory MP Roger Gale called Cameron a "dead man walking".
A number of Cabinet ministers have come out in support of Mr Johnsn.