Women will break the current record of 84 serving at the same time in the US House of Representatives.
With ballots still being counted across the US, women have won 75 seats and are assured of victory in nine districts where women are the only major-party candidates.
From the Women's March opposing President Donald Trump the day after he was inaugurated in January 2017 through a stream of sexual assault accusations later that year that sparked the #MeToo movement, outrage and organising by women have defined Democratic politics for the midterm elections.
More than 230 women, many of them first-time candidates, were on the general-election ballots in House races.
Despite the gains, men will continue to hold the vast majority of House seats.
"This is truly the year of the woman everywhere," said Thomas Perez, chairman of the Democratic National Committee.
Coming away with decisive wins were incumbent senators Elizabeth Warren in Massachusetts, Amy Klobuchar in Minnesota and Kirsten Gillibrand in New York, all high-profile Democrats.
Among the most notable new female House members are Alexandria Ocasio-Cortez, 29, the youngest woman elected to Congress; Ilhan Omar and Rashida Tlaib, the first Muslim women elected to the House; Sharice Davids, a lesbian, lawyer and former mixed martial arts fighter; and Debra Haaland, the first Native American women.
In addition Texas for the first time elected Latina woman, both Democrats, and Massachusetts elected a black woman to the House for the first time.
Women also were responsible for a several Democratic gains that helped the party retake control of the House.
