The incumbent Jen Psaki is set to leave the post next week.
Ms Jean-Pierre takes on the role as the White House faces an uphill battle to help the Democrats hold onto the US House and Senate in this autumn’s mid-term elections, with the Biden administration struggling to address Americans’ concerns about soaring inflation and the state of the economy.
She also comes into the job as Mr Biden faces a daunting array of foreign policy challenges, including the ongoing Russian invasion of Ukraine and North Korea’s escalating nuclear testing programme.
Mr Biden is set to visit South Korea and Japan later this month and Europe in June.
He is also bringing back long-time Democratic strategist Anita Dunn as his senior adviser.
She had served in the White House last year for several months after Mr Biden was sworn into office.
“Karine not only brings the experience, talent and integrity needed for this difficult job, but she will continue to lead the way in communicating about the work of the Biden-Harris administration on behalf of the American people,” Mr Biden said in a statement praising Jean-Pierre, who has served as his principal deputy press secretary since Inauguration Day.
Ms Psaki, who leaves the White House on May 13, praised her successor as a “partner in truth”, noting the significance of the history-making appointment.
“Representation matters and she is going to give a voice to so many and show so many what is truly possible when you work hard and dream big,” Ms Psaki said.
Taking the lectern briefly while Ms Psaki briefed the press on Thursday, Ms Jean-Pierre said she was “still processing” the significance of her appointment, calling it “an honour and privilege to be behind this podium”.
“This is a historic moment, and it’s not lost on me,” she said. “It’s a very emotional day.”
Ms Psaki said Mr Biden offered the job to Ms Jean-Pierre on Thursday in the Oval Office.
White House staffers were gathered after the offer and greeted Ms Jean-Pierre with applause and champagne, an official said.
Ms Jean-Pierre had occasionally taken the lectern in the press briefing room instead of Ms Psaki and more frequently held off-camera “gaggles” with reporters when Mr Biden was traveling on Air Force One.
She travelled with Mr Biden to Europe last fall and in March instead of Ms Psaki, who had tested positive for Covid-19 before both trips.
Before joining the Biden presidential campaign, Ms Jean-Pierre was the chief public affairs officer of the progressive group MoveOn.org and a former political analyst for NBC and MSNBC.
She also worked in political affairs in the Obama White House and on his re-election campaign.
The press secretary is responsible for holding daily briefings with the news media and leading a department of more than a dozen staff who help address queries from the press.
When she took the job, Ms Psaki, who has two young children, said publicly she aimed to remain in the job for about a year.
She is expected to join MSNBC later this year.