Margaret Ferrier travelled in and around Glasgow and to London in September 2020 having tested for the virus.
While awaiting results, the independent MP for Rutherglen and Hamilton West spoke in the Houses of Parliament and visited elsewhere in London.
A court heard she then took the train home to Glasgow after being told she had tested positive for Covid-19.
Ferrier, of Cambuslang, admitted that she had culpably and recklessly exposed the public “to the risk of infection, illness and death” at a hearing at Glasgow Sheriff Court on Thursday.
Sentencing was deferred pending legal reports until September.
During the hearing, the court heard Ferrier did a test for Covid-19 on September 26 after showing symptoms, including a cough.
The next day she read to a congregation of about 45 people at a mass in St Mungo’s Church, Glasgow, before heading to Vic’s bar in Main Street, Prestwick, South Ayrshire.
She then travelled to London by train on the September 27 and spoke in the Commons later that day.
A short time after, she found out she had tested positive for the virus.
The court heard Test and Protect had tried to contact her three times and left two voicemails at about 10am that day before Ferrier returned the call at about 2pm, almost four hours later.
Ferrier then returned to her hotel, where she spent the night, before heading back to London Euston and taking the train home to Glasgow, knowing she had Covid-19.
The MP, who was present in court on Thursday, informed Patrick Grady, the then chief whip, and who she had spoken to while in the Commons.
She had also sat at a table with DUP MP Jim Shannon, who was identified as a close contact.
He was told to test and isolate in his hotel room. He tested negative.
Mr Grady was told the following day at a meeting at the Speaker’s Office in the House of Commons that Ferrier needed to report her actions to Police Scotland.
Ferrier contacted police and informed them of her breach before sending out a statement on her social media.
In January 2021, she was charged with culpable and reckless conduct, the court heard.
Prosecutor Mark Allan told the court: “The conduct amounted to a reckless disregard of public safety.”
He read out statements from medical experts who assisted Police Scotland in their investigation on Ferrier.
One of them was from public health expert Dr Andrew Riley who told officers: “On receiving the positive result, the accused should have immediately self isolated and sought public health advice on what to do next,” adding that Ferrier would have been infectious “probably for the next seven to 10 days.”
He said she had “significantly increased the risk of harm to both individual and public health”.
A statement from microbiologist Dr Robin Howe said Ferrier should have self-isolated when showing symptoms.
He said her movements in Glasgow and to London “put other individuals at unnecessary and increased risk of Covid-19”.
He said 10% of contacts of an individual who has the virus will develop the infection.
Ferrier had the SNP whip removed in 2020 after the allegations emerged.
She has come under pressure to resign from her seat, but remains an MP.