Theresa May has rejected international development minister Lord Bates' resignation hours after he dramatically quit at the despatch box.
The peer sent shockwaves through the usually restrained House of Lords when he walked out of the chamber after quitting because he was "ashamed" he had failed to turn up on time.
No 10 said his resignation had been refused because it was judged "unnecessary".
Lord Bates arrived late for an oral question session where he was listed to respond to a query from Labour peer Baroness Lister of Burtersett.
When he did make it to the despatch box, the peer told Lady Lister he was "thoroughly ashamed" and would be offering the Prime Minister, who is on a trade mission to China, his resignation.
Lord Bates said: "With the leave of the House I wonder if you would permit me to offer my sincere apologies to Baroness Lister for my discourtesy for not being in my place to answer her question on a very important matter at the beginning of questions.
"During the five years of which it has been my privilege to answer questions from the despatch box on behalf of the Government I have always believed we should rise to the highest possible standards of courtesy and respect in responding on behalf of the Government to legitimate questions of the legislature.
"I am thoroughly ashamed at not being in my place, I therefore shall be offering my resignation."
As he passed the red benches on his way out of the chamber, cries of "no!" could be heard from shocked peers.
Downing Street said Lord Bates was a "diligent" minister who took his responsibilities to Parliament seriously.
A No 10 spokesman said: "With typical sincerity, Lord Bates today offered to tender his resignation after missing the start of an Oral Questions session in the House of Lords, but his resignation was refused as it was judged this was unnecessary.
"As a hard-working and diligent minister, it is typical of his approach that he takes his responsibilities to Parliament so seriously.
"He has received support from across the House and we are pleased that he has decided to continue in his important roles at the Department for International Development and HM Treasury."