Jacob Rees-Mogg is self-isolating after one of his children showed symptoms of Covid-19.
The child is understood to be awaiting results of a coronavirus test.
The Tory Commons leader was scheduled to appear for the weekly Business Questions session in the House this morning.
But instead, Deputy Chief Whip Stuart Andrew arrived in his place, and explained Mr Rees-Mogg was in quarantine with his family.
He said: “A member of the Leader of the House’s household is awaiting a Covid test result after having been symptomatic.
“The Leader is therefore self-isolating with his family, so I’ve had the good fortune…to be asked to reply.”
Mr Rees-Mogg wrote on Twitter: “Many thanks to Stuart Andrew for standing in for me at business questions.
“One of my children was tested for Covid-19 last weekend after displaying symptoms.
“In accordance with Government guidance, the household has been in self-isolation while we await the test result.”
Labour’s Shadow Commons Leader Valerie Vaz said: “We all wish the Leader of the House and the whole Rees-Mogg family well, and we know it had to be something very, very serious for him not to be here.”
Mr Rees-Mogg, who is MP North East Somerset, has been married to Helena De Chair since 2007.
The couple have six children, Peter, Mary, Thomas, Anslem, Alfred and Sixtus.
They also have a nanny, Veronica Crook, who has worked and lived with the family for more than 50 years, and looked after Mr Rees-Mogg when he was a child.
SNP Commons leader Tommy Sheppard joked he would miss being “patronised in the flesh” by Mr Rees-Mogg.
The MP for Edinburgh East has contributed remotely to proceedings on several occasions during the coronavirus pandemic.
Mr Sheppard told the Commons: “Can I also wish the Leader of the House and his family well. I can hardly hide my disappointment at his absence.
“After five long months of my own absence from this chamber, and sometimes problematic communication through the virtual proceedings, I have been looking forward to being patronised in the flesh rather than over the internet.”