She fought off the challenge of Pam Duncan and Monica Lennon to win the backing of local members as the replacement for disgraced MP Eric Joyce.
Mr Joyce was kicked out of the party after committing an assault in a House of Commons bar, and now represents the constituency as an independent.
His ejection sparked a controversial selection process which became mired in allegations of vote-rigging, igniting a chain of events that ultimately brought one of Scotland's key industrial complexes to the brink of closure.
Speaking after her selection, Ms Whitefield conceded that the party will have to work hard to regain people's trust following Mr Joyce's crimes and the fraught selection process to replace him.
"I am delighted and greatly honoured to have been given the opportunity to work for the Labour party and serve the people of Falkirk in the run up to the general election and I hope they will put their trust in me," she said.
"The next step is all about campaigning, getting on to the streets and into the communities and making sure that they understand what the Labour party stands for, that we care and can make a difference for them and will stand up for them.
"It's not good enough that families are working hard but that work doesn't pay, or that people have to make the choice between heating and eating, and I want to give those people a voice here in the constituency and at Westminster.
"This is the start of working hard to regain people's trust. It's time to move forward and look to the future.
"I think the party is in very good spirits tonight.
"I think this will unite us. We will look to the future, and be out there working hard to regain people's trust, which they have given to us in the past, and to earn that trust for the future."
Earlier this year, Unite was accused of signing its members up to the Falkirk Labour Party to ensure the union's favoured candidate, Karie Murphy, was selected as the next general election candidate.
The union was cleared of any wrongdoing in an internal inquiry by Labour but the local party was put under "special measures", which meant that the power to draw up the shortlist was taken away from it, and was conducted centrally.
The councillor who blew the whistle on the claims of vote-rigging was subsequently snubbed in the selection process.
Former Falkirk Council leader Linda Gow, who alerted the party to allegations against the trade union Unite, said she was "disappointed" not to be on the final shortlist.
Meanwhile, Police Scotland chief constable Sir Stephen House is looking into separate allegations against Unite concerning alleged intimidation of senior members of Ineos staff.
The union was involved in an industrial dispute with the Grangemouth refinery, which was first sparked by the vote-rigging allegations.
Unite and site owners Ineos became embroiled in a bitter dispute, initially over the treatment of Unite convenor Stephen Deans, who was involved in the Labour selection row as chairman of the constituency party.
The dispute dramatically widened to threaten the future of the entire site, with Ineos warning that it would close without fresh investment and changes to pay, pensions and other conditions.
Unite accepted the changes, most of which are due to come into force in January, and the company has since announced up to 200 job losses in the ensuing cost-cutting drive.