The inauguration committee unveiled on Twitter, early on Thursday (14Jan), that Gaga would perform America's national anthem, "The Star-Spangled Banner", at the event, being held in Washington, D.C. on Wednesday 20 January (21) to mark Biden and Harris being made President and Vice President of the United States respectively.
Gaga has been a vocal campaigner for Biden, urging people to vote for the then-Democratic candidate during a Pittsburgh, Pennsylvania, drive-in rally last November (20).
While Lopez, another active Biden campaigner, is set to join the likes of Demi Lovato, Justin Timberlake, and Jon Bon Jovi, also performing at the inauguration which will be televised across multiple channels in the U.S. Amanda Gorman will give a poetry reading, the tweet said.
Gaga and Lopez are the latest stars to be confirmed for the event, following news that Tom Hanks will host the star-studded prime-time special entitled "Celebrating America".
Presidential Inaugural Committee CEO, Dr Tony Allen, said, "This inauguration presents a unique opportunity to spotlight the resilience and spirit of an America United."
"We have witnessed countless heroes this past year step up to the frontlines and serve their fellow Americans, so we are telling their stories, spreading their collective light, and celebrating the best of our country and its people with this prime-time program."
"Our first priority is safety - so while many of us will be watching safely from our homes, we are creating real moments of connection that highlight a new inclusive American era of leadership that works for and represents all Americans."
TV networks have previously broadcasted concerts and other performances hosted by inaugural committees, and the special is effectively replacing that coverage.
The event will also stream on the committee's YouTube and social media channels, Amazon Prime Video, Twitch, and Fox's NewsNOW.