The Conservatives accepted £37.7m from wealthy donors during the final quarter of 2019 in a bumper election funding bid that surpassed all the other political parties combined.
The Liberal Democrats overtook Labour with £13.6m, as pro-Remain donors threw their weight behind the smaller party.
Donations hit the highest level since records began during the final three months of 2019, with £70.1m reported by all the political parties, the watchdog found.
The figures cover the December general election, showing the cash Mr Johnson was able to funnel into his decisive victory at the polls.
Louise Edwards, director of regulation at the Electoral Commission, said: “In the final three months of 2019, political parties reported accepting the highest value of donations in one quarter since our records began.
"The value of the donations accepted by parties in the last quarter exceeded the previous high, from 2017, by almost £28 million.
“While there is no limit to the value of donations political parties can accept, spending rules are in place during elections to keep the campaign fair.
“Publishing this data allows voters to see clearly how parties in Great Britain are being funded, enhancing public confidence and trust in our democratic processes.”