The Conservatives reported three times as many donations as any other party at the start of 2018.
The Tories said they got £4.7m in the first three months of the year, compared with £1.4m given to Labour and £564,000 to the Liberal Democrats.
Leading Tory donors include Ehud Sheleg, an Israeli-born businessman who recent media reports have suggested could become the party's treasurer.
The party also received a £582,358 bequest.
Labour's principal financial supporters over the period, according to figures from the Electoral Commission, were leading trade unions, with Unite giving it £450,027.
The party also received £1.2m in "Short" money, public funding set aside for opposition parties in Parliament.
Mr Sheleg, the owner of the Halcyon art gallery in London, has become a major Tory benefactor in recent times, giving the party £250,000 in the run-up to last year's snap election.
Between January and March, he donated an additional £500,000.
Reports have suggested Mr Sheleg, who has a number of business interests in the West Midlands, could become the party's chief fundraiser.
Sir Michael Davis, the party's chief executive who himself gave the Tories £267,000 during the period, has continued to act as treasurer since being promoted to the top job after last year's election.
The bequest is listed as coming from Gerda Winder. A woman of that name died aged 86 in Colchester in April last year.
Will Quince, the Conservative MP for Colchester, told the Huffington Post the bequest was "incredible".
"A lot of people knew of her, but not much about her," he said. "Clearly she must have been a keen supporter of the party." It is believed Ms Winder came to the UK from her native Germany in her 20s.
New Anti-Brexit party Renew, whose founder Chris Coghlan recently announced his departure, received £111,671 in donations over the three-month period.
The Liberal Democrats received £25,000 from Pimlico Plumbers, whose owner Charlie Mullins was once a Conservative donor but who has become an outspoken critic of Brexit.
Neither the SNP nor UKIP reported any donations above the £7,500 threshold. But UKIP took out a £86,379 loan, taking its total outstanding borrowings to £390,379 at the end of March.
Its current leader Gerard Batten said in April that UKIP had been saved from the risk of insolvency after it received donations worth almost £300,000 from members. He had emailed branch officials to say the future of the party was in question if they did not raise the money for running costs.
Separately, the Electoral Commission has announced it is investigating money paid by Mid and East Antrim Council to sponsor a table at a DUP MP's constituency dinner.
Ian Paisley hosted the event at Tullyglass Hotel, Ballymena, last year. The commission is focusing on £1,500, which it described as a "donation" to Mr Paisley. He insists the money was paid directly to the hotel.