Boris Johnson pocketed more than £700,000 in outside earnings in the last year – more than any other MP.
The figure was described as “obscene” and evidence of the “sickening inequality in this country”, as struggling nurses are having to use foodbanks to survive.
Mr Johnson was also able to use an £850,000 political war chest from personal donations.
Labour’s Louise Haigh said: “While the PM has been raking in obscene amounts of money on top of his prime ministerial salary, hundreds of thousands are relying on foodbanks, unable to heat homes and struggling to make ends meet.
“His contempt for the people that need government support the most is exactly why we have such sickening inequality in this country.”
Mr Johnson also earned £80,000 as an MP and £8,000 for the time he has been Prime Minister, making a grand total of £1.6million.
A survey by Cavell Nurses’ Trust has found that 9% of nurses rely on foodbanks.
Four million children are in poverty in the UK and more than 800,000 people are on zero-hours contracts. The average full-time wage is £29,009.
While the information for the outside earnings of each MP is in the public domain, a new tool by tech firm Set Reset has totted up the overall sums.
Tories were the top earners, with 81% taking home an average £41,000 more than their MP salary in the last financial year.
Labour plans to ban MPs from second jobs with the exception of those maintaining professional registrations like nurses.
Shadow Cabinet Minister Andrew Gwynne said: “The Conservatives have spent years protecting the super-rich and big business and cutting public services for everyone else.
“This lays bare the inequality in our country. While Boris Johnson has been raking it in, his government has left millions in poverty, schools begging parents for funds and a record number of families turning to foodbanks.
“The Tories are not on your side. Labour will deliver real change, where wealth and power are in the hands of the many, not the few.”
Labour also aims to stop political donations from people who don’t pay tax in the UK in a crackdown on dark money in politics.
And they would make it a legal requirement for parties to declare big money donors who attend events organised by the party.
Shadow Cabinet Office Minister Jon Trickett said: “Under the Tories politics and government is in serious danger of becoming a playground for the rich and powerful, with decisions often made behind closed doors in the interests of a small few, at the expense of the many.
"This is very worrying for our democracy.”