It is officiially on, American citizens.

On Tuesday afternoon, Joe Biden announced that he had selected California Senator Kamala Harris as his running mate in the 2020 Presidential Election.

Harris, former nominee herself for the Oval Office, now becomes the first-ever Black woman to be nominated for Vice President  of the United States.

"I have the great honor to announce that I’ve picked @KamalaHarris — a fearless fighter for the little guy, and one of the country’s finest public servants — as my running mate," Biden Tweeted today.

Referencing his late son, Biden added:

"Back when Kamala was Attorney General, she worked closely with Beau.

"I watched as they took on the big banks, lifted up working people, and protected women and kids from abuse. I was proud then, and I'm proud now to have her as my partner in this campaign."

Harris is the fourth woman on a major presidential ticket, following Democratic vice presidential nominee Geraldine Ferraro in 1984, Republican vice presidential nominee Sarah Palin in 2008 and Democratic presidential nominee Hillary Clinton in 2016.

A former prosecutor, she had been on a list of possible Vice Presidential candidates for months.

The first-term senator was elected to Congress in 2016 after serving as the California attorney general since 2011.

She challenged Biden on stage at the first Democratic debate late last year, calling out the former VP for what she outlined as his previous stance in the 1970s, opposing mandatory school busing legislation.

Such an aggressive approach saw Harris fly toward the top of the polls for a brief period of time.

However, by December, Harris said her campaign had ran out of funds and she dropped out the race.

Upon suspending her campaign, Harris vowed to "do everything in my power to defeat Donald Trump and fight for the future of our country and the best of who we are.”

As for how Hollywood is reacting to the news?

Let's go to social media!

George Takei: "Biden/Harris will begin to heal our nation. From the devastation of the virus to systemic racism, from the economic collapse to the looming climate crisis, we have chosen two great leaders who will lift us up together, toward a new future, toward a new America. #BidenHarris2020."

John Legend: "Very happy for our friend and Senator and future Vice-President, @KamalaHarris, and very much looking forward to voting for the Biden-Harris ticket to begin the difficult work of recovering from this nightmare presidency and building an even better future."

Debra Messing: "BREAKING NEWS: Joe Biden has chosen KAMALA HARRIS as his running mate. And . I. AM. ALL FOR IT!!!!!!!!! I'm so excited!!!!!!!!!"

Whoopi Goldberg: "Sen.KamalaHarris this is a great moment. Let's take care of her and make sure we are supportive of her because this is a no nonsense race and she is ready. Go Kamala!"

Mark Hamill: "The next Vice President of the United States of America."

LeBron James: "Congrats and well deserved Sen. Kamala Harris!! Love to see and support it! Appreciate you JB."

Sarah Paulson: "The sexist and racist political attacks on @KamalaHarris have already begun. Let's demand that the media keep these ignorant, bad-faith attacks out of their 2020 election coverage. Let her know: #WeHaveHerBack"

Elizabeth Banks: "Congrats to all of us, especially @joebiden because @kamalaharris is a powerhouse #bidenharris2020."

WHO DO YOU WANT TO WIN THE 2020 PRESIDENTIAL ELECTION?