Truss' candidacy received 81 326 votes, while Sunak received the support of 60 399 voters.
Over the past few weeks, Truss and former British finance minister Rishi Sunak have competed for the support of the formation's approximately 160 000 members, who have voted by traditional or electronic mail.
The current Prime Minister, Boris Johnson, who resigned last month, will travel with Truss to Balmoral Castle in Scotland on Tuesday for the handover and to hold audiences with Queen Elizabeth II.
I am honoured to be elected Leader of the Conservative Party.
Thank you for putting your trust in me to lead and deliver for our great country.
I will take bold action to get all of us through these tough times, grow our economy, and unleash the United Kingdom’s potential. pic.twitter.com/xCGGTJzjqb