Boris Johnson was paid more than £276,000 to give a speech in the US a month after leaving Downing Street.
The former prime minister addressed a Council of Insurance Agents and Brokers conference in Colorado Springs in October, giving a 30-minute speech and a 45-minute "fireside chat".
Reports at the time suggested he got around $150,000 (£126,743) but his official declaration shows he was paid £276,130.
Organisers also covered transport and accommodation costs for Mr Johnson and two staff.
An update to the MPs' register of interests, published on Thursday, said the money covered eight and a half hours of work, making his fee almost £32,500 an hour.
Media mogul Rupert Murdoch also paid £11,559 to fly the ex-PM to a business meeting in Montana after the conference, the register notes, providing him and his two staff with accommodation and "hospitality".
It was around this time that the MP also went on holiday with his wife and two children, and more details of this funding was revealed.
Gatwick Airport allowed the Johnson family to use its Sussex suite on 7 October and 22 October - the latter being the date he flew back amid speculation of another leadership bid - at a cost of £1,584 each time.
Lord and Lady Bamford - the chairman of JCB and his wife, who have made multiple donations to Mr Johnson - allowed the Johnsons to use their accommodation in the Dominican Republic at an estimated value of £3,500.
The Register of Members' Financial Interests - where all MPs must declare any donations, wages or gifts - also revealed former prime minister Theresa May was paid £97,000 to give a speech to the Apax Partners law firm in New York in October.
She received a further £8,000 for an hour-long virtual speech two days before for World 50 - described as "a private community for senior-most executives from globally respected organisations to intimately share ideas, solutions and collaborative discovery free from press, competition and solicitation".
Former chancellor and ex-health secretary Sajid Javid was also paid £36,000 to give a speech to clients of Deutsche Bank on 10 October.
More details of financial backing for the Tory leadership contests were also revealed.
Liz Truss received £33,265.48 from British businessman and prominent Brexit support Jon Moynihan to "cover winding up costs for my leadership campaign", which included transport, research, office services, and supporter events.
Penny Mordaunt, who missed out on becoming prime minister twice this year, also reported a £20,000 donation to her leadership campaign on 14 October from Tory peer Lord Harris.
Other notable entries include a £10,000 donation to Labour deputy leader Angela Rayner from green energy supplier Ecotricity Group, as well as a book advance of £6,150 for Nadhim Zahawi, who served as chancellor over the summer.
Tory MP Jonny Mercer was also paid £9,840 to take part in a TV show, and £5,000 was given to Labour MP Jess Phillips for her appearance on Have I Got News For You.