The vote will take place between 6 p.m. to 8 p.m., the BBC reported.
"A change of leadership in the Conservative Party now would put our country's future at risk and create uncertainty when we can least afford it," May told reporters outside 10 Downing Street.
"I will contest that vote with everything I have got."
"The new leader would not have the time to renegotiate the withdrawal agreement and get the legislation through Parliament by March 29," May added, referring to the date the UK is officially scheduled to leave the bloc.
"So one of their first acts would have to be extending or rescinding Article 50, delaying or even stopping Brexit when people want us to get on with it."
The challenge to May's position came after the required 48 letters calling for a contest were delivered. She will need the backing of at least 158 conservative members of Parliament to see off the challenge.
The ruling party has amassed enough support to challenge May's leadership, said a statement by Graham Brady, a member of the 1922 Committee parliamentary group.
If May loses, the Conservatives will elect a new leader through an internal process. If she wins, the party will be barred from holding a similar vote for a year, according to its rules.
In case she is ousted as Conservative leader, she would still be expected to stay on as a caretaker Prime Minister til a new leader is selected by the party, a process that could take six weeks.
The 48 letters came in the middle of a crisis generated by May's decision to delay the crucial vote on her Brexit deal. She postponed the vote after eurosceptic Tories and opposition members expressed disagreement with the agreement.
On Tuesday, the Prime Minister contacted European leaders to try to secure concessions intended to persuade Parliament to approve the agreement.
Following the no-trust vote announcement, British Foreign Secretary Jeremy Hunt, tweeted: "I am backing @theresa_may tonight. Being PM is the most difficult job imaginable right now and the last thing the country needs is a damaging and long leadership contest."
Home Secretary Sajid Javid said: "The last thing our country needs right now is a Conservative Party leadership election, which will be seen as self-indulgent and wrong. PM has my full support and is the best person to ensure we leave EU on March 29."
(Only the headline and picture of this report may have been reworked by the Business Standard staff; the rest of the content is auto-generated from a syndicated feed.)