Mr Elliot described the "huge honour" of serving as co-chairman but has decided to step down in the wake of Boris Johnson's exit as party leader.
In a statement, he said: “Serving as co-chairman of the Conservative Party has been a huge honour and privilege.
"I would like to thank my various co-chairmen, colleagues on the Party Board, the National Convention, the excellent senior staff at CCHQ and of course all our professional staff, members and volunteers across the country.
"I would like to thank Boris Johnson for appointing me, and wish Liz Truss every success in leading our great country, particularly given the challenges of the winter ahead.”
Ben Elliot (right) has stepped down as co-chairman of the Conservative Party
PA/Twitter/Ben Elliot
Liz Truss speaks after winning the Tory leadership contest
HANNAH MCKAY
Conservative Party chief executive Darren Mott said: “The whole Conservative Party wants to thank Ben Elliot for his tireless service over the past three years.
“Without his incredible efforts, the 2019 landslide would not have been possible. We wish him all the best in his future endeavours.”
It comes after Ms Truss defeated Rishi Sunak in the Tory leadership race, winning by a convincing margin.
Ms Truss won with 81,326 votes from the party membership, compared to Mr Sunak’s 60,399.
She said it was an "honour" to be announced as the winner, after a “hard-fought campaign” against Mr Sunak.
Ms Truss added: “I also want to thank our outgoing leader, my friend, Boris Johnson.
“Boris, you got Brexit done, you crushed Jeremy Corbyn, you rolled out the vaccine and you stood up to Vladimir Putin. You were admired from Kyiv to Carlisle.”
Ms Truss' first task will be a trip to Balmoral, as the Queen has opted not to travel back to London for the customary Buckingham Palace address with the Prime Minister in waiting.
The Queen will receive Mr Johnson on Tuesday at her Highlands home, where he will formally tender his resignation.
This will be followed by an audience with the new Tory leader, where Ms Truss will be invited to form a government and take over as PM.
It comes after weeks of sometimes bitter in-fighting among allies of the former Chancellor and Foreign Secretary.