Data from the social media giant shows the Tories spent £86,020 on targeted advertising on Facebook in the 30 days to August 17- more than they spent over the previous 60 days (£54,603).
The 30-day total is more than three times the amount spent by the Labour Party (£23,135) during the same period.
The Liberal Democrats were the top spenders over the past 90 days with £151,137, but forked out just £4,027 in the 30 days to August 17.
The Brexit Party also appeared to reduce its spending – paying £11,461 in the past 30 days, compared with £83,155 over 90 days.
The Tory advertising push comes as the Government plots an estimated £100 million in spending on information to prepare people and businesses for a no-deal Brexit.
Many of the Conservative-funded Facebook adverts targeted political opponents, including one in the past week specifically aimed at constituents of former Tory MP Sarah Wollaston.
One of several similar versions of the advert aimed at residents of Totnes, Devon, read: “Should your MP, Sarah Wollaston, be ignoring YOUR vote to leave the EU? Tell her YES or NO now.”
Ms Wollaston, an outspoken opponent of Brexit, left the Conservatives in February to form Change UK, before switching to the Liberal Democrats.
Other adverts took aim at Labour leader Jeremy Corbyn, Scotland First Minister Nicola Sturgeon and Lib Dem leader Jo Swinson, with one reading: “Jeremy Corbyn, Jo Swinson and Nicola Sturgeon want to pick and choose which votes they respect – ignoring 17.4 million Leave votes.
“Add your name now to show them they can’t get away with it.”
The adverts echo tactics by pro-Brexit campaigns such as Leave.EU and Britain’s Future, which targeted constituents of Remain-supporting MPs, urging the public to email them or even deselect them.
The messaging comes as the Prime Minister’s new-look Government promises to leave the EU on Halloween, with or without a deal.
Adverts paid for by the Conservatives but posted to Mr Johnson’s own Facebook page repeatedly highlighted that promise, with one example reading: “I’m going to deliver Brexit by the 31st of October – so we can invest in the NHS, schools, housing and police.
“We’ve got a fresh opportunity to get things done. It’s time to get the UK back on the road to a brighter future.”
The majority of the adverts encouraged recipients to share their views by signing forms or taking surveys that allowed the party to subsequently target them with further advertising by email, online or by post.
The party also spent £5,819 on adverts to residents of Brecon and Radnorshire, which the party lost to the Lib Dems in a by-election earlier this month.
Several members of Mr Johnson’s advisory team previously worked on the official Vote Leave campaign, which came under scrutiny for its use of targeted Facebook advertising during the referendum campaign.
Vote Leave’s campaign director, Dominic Cummings – now Mr Johnson’s top adviser – was criticised by MPs for failing to give evidence on the campaign’s use of Facebook to reach voters.