Jacob Rees-Mogg is self-isolating after one of his children developed symptoms of Covid-19.
The Commons Leader's child is understood to be awaiting results of a coronavirus test.
Mr Rees-Mogg, 51, 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.
The Mirror reports 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.
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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."
