Biden made the grim mistake during an appearance at the White House Conference on Hunger, Nutrition, and Health in Washington. Walorski was one of four lawmakers who sponsored legislation pushing for the conference last year.
The Republican was killed in a tragic car accident along with two of her staffers in early August.
The president attempted to give her a shout-out along with others during his address.
"I want to thank all of you here, including bipartisan elected officials like … Senator Braun, Senator Booker, Representative … Jackie, Jackie are you here?" Biden said. "I think she was going to be here to help make this a reality."
While a tribute to Walorski was scheduled to play at the event, it was not presented while Biden or the White House pool were there.
Walorski, 58, and her staffers, communications director Emma Thomson, 28, and district director Zachary Potts, 27, were all killed in an Aug. 3 crash. Police would later confirm that Potts, the driver, had somehow turned into oncoming traffic.
"A northbound passenger car traveled left of center and collided head-on with a southbound sports utility vehicle. All three occupants in the southbound vehicle died as a result of their injuries: Jackie Walorski, 58, Elkhart, Indiana Zachery Potts, 27, Mishawaka, Indiana Emma Thomson, 28, Washington, DC," the Elkhart County Sheriff’s Office told Fox News Digital last month.
"The sole occupant of the northbound vehicle, Edith Schmucker, 56, Nappanee, Indiana, was pronounced deceased at the scene," the statement continued.