There was no immediate announcement of his successor, who will become Britain's fourth finance minister this year.
"I’m told that Kwasi Kwarteng is being sacked as Chancellor as Liz Truss prepares to reverse the mini-Budget,” Steven Swinford, Political Editor of The Times, said on Twitter.
Earlier, Kwarteng said he was dropping his plan to scrap the top rate of income tax, which had caused an uproar including among some lawmakers within his own Conservative Party and helped trigger turmoil in financial markets.
Kwasi Kwarteng reversed the decision to cut taxes for the highest earners after spending days defending the move that triggered market turmoil and firestorm of criticism
At the start of the governing Conservative Party's annual conference, Kwarteng and Prime Minister Liz Truss have been forced to defend a plan that failed to spell out the financing for deep tax cuts combined with an expensive package of energy subsidies.
Kwasi Kwarteng’s first policy announcement as UK finance minister appears to be a bigger disaster for the British economy that Brexit.
Former Finance Minister Kwasi Kwarteng announced several fiscal measures as he set out a mini-Budget designed to boost Britain's economic growth. Here's all you need to know
"The estimated costs of our energy plans are particularly uncertain given volatile energy prices, but based on recent prices, the total cost of the energy package for the six months from October is expected to be around 60 billion pounds," he told parliament.