The billionaire businessman comes to power with Democratic majorities backing him in both the state house and senate.
WATCH: Gov. JB Pritzker's full inaugural address
Pritzker ushered in his administration with talk of hope and kindness and promise to get things done for the people, as well as the need to work together to deal with the challenges facing Illinois.
READ: Full text of Gov. JB Pritzker's inaugural address
He got a standing ovation as he was welcomed on stage with his family, casting his vision for the future of the state.
"As your governor, I'll be committed to helping us become the fastest growing big state economy in the nation. I will be our state's best chief marketing officer to attract jobs and businesses to Illinois," he said.
"I have not been this excited about the state of Illinois in a good while," said Rep. Danny Davis.
Pritzker also addressed the hard realities he's inheriting - billions of dollars of unpaid bills and pension obligations - laying out his plan for a balanced budget.
"The current tax system is simply unsustainable," he said. "Others have lied to you about that fact. I won't. The future of Illinois depends on the passage of a fair income tax."
"We contend every day with an economy that gives too little and takes too much," Pritzker added. "That allows passion and work ethic to be overwhelmed by student loans, unexpected health emergencies and the rising cost of living."
Pritzker's words were welcome news for the Waukegan Mayor Sam Cunningham.
"We are going to have the opportunity to work with an administration not only from the state but down to the local to make sure our residents that come to us first, we are the first line of defense, to make sure we have a voice for them," Cunningham said.
Pritzker called for providing broadband internet statewide, and a budget that wasn't balance on the backs of the starving, the sick and the suffering, a clear shot at his predecessor, Bruce Rauner.
He then spoke about the need for change in the way the state raises money to pay its bills, and then had a message for those who would stand in his way.
"I'm not naive about what it will take to do this. All who enter a discussion about our state's budget and a fair tax system in good faith will be welcomed to the table. But if you lead with partisanship and scare tactics you will be met with considerable political will," Pritzker said.
Senate Republican Leader Bill Brady said he was not offended by the remark.
"We Republicans believe reducing the burden on families and business is more productive and conducive to economic growth," Brady said. "He believes, obviously strongly, the way he does, but he's been very clear that aside from that issue there's many issues we can work together on."
Pritzker has also made a $15 minimum wage a top priority. Sam Toia, president and CEO of the Illinois Restaurant Association, hopes it can be introduced gradually over a five to six year period.
"I do believe Governor Prtizker and his administration will listen, I think communication is the key to success, I think he wants people at the table, not on the menu," Toia said. "So I believe that as long as we're at the table, communicating, hopefully we can get to a middle ground."
Pritzker talked about the importance of diversity and inclusion, and bringing economic vitality to parts of the state that have felt left out.
"I have built a cabinet of people who bring with them experiences I don't share from communities I did not come from, with expertise I don't have, because to lead well, all of Illinois must be represented in the decision making," he said.
"I think this is a good day," said State Rep. Will Davis, Assistant Majority Leader. "We suffered the last four years under the past administration because he did not have the willingness to work with the General Assembly to try and get the real important things done here in the state of Illinois. I certainly don't think we're going to have those challenges with our new governor."
"A great warmth here, a great camaraderie. I've seen people here that I haven't seen in many years and it's just warm and I think people are excited about the future," said Desiree Rogers, CEO of Choose Chicago.
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But with great hope comes big expectations, especially with Democrats firmly in control.
"Look, there's a lot of pressure on us all because of the condition this state has been left in," said State Rep. Greg Harris, House Majority Leader.
"I've heard a lot of politicians make promises and so I'm not holding my breath, but it's the right sentiment and I think the teachers of Chicago and all of us should do what's necessary to hold the politicians to those commitments," said Chicago Teachers Union President Jesse Sharkey.
Pritzker capped off the night with celebratory Inaugural Ball, a lavish party to usher in a new day.
"I think it's very well put together," said State Rep. Lou Lang. "I'm sure JB, who does everything first class, is going to have a wonderful evening for all of us."
Maroon 5 took the stage after the first dance, wowing the crowd and ramping up the festivities.
"This is amazing. It is for the people, all the proceeds are being donated to charity from what I understand, so we are all here just to have a great time," said Sanovia Reynolds Parks, campaign volunteer.
One of the charities is the Illinois State Fair Foundation; the other is Cabrini Green Legal Aid, which helps low income Chicagoans maneuver the legal system. The executive director of the organization was a colleague of Lieutenant Governor Julianna Stratton.
"Being the recipient of this award was quite a surprise um Juliana called me during the week at like 10 o'clock at night and gave us the big news and so I was like 'What is going on!' Um, this is so exciting," said Esther Franco-Payne, executive director CGLA.
With over 1,000 people in attendance, the ball raised at least $250,000 for those charities.
The day started at First Presbyterian Church in Springfield with an interfaith ceremony.
Before the swearing-in of Governor-elect Pritzker and Lieutenant Governor-elect Juliana Stratton, they will take the oath of office with a super majority at the state capitol where Democrats now fully control the state legislature.
Pritzker campaigned with some bold promises, including raising the minimum wage, and legalizing recreational marijuana and sports betting.
For the most part, Pritzker and Democrats won't need Republicans to try and push through their agenda, but nevertheless, Inauguration Day is beginning with good faith promises of bipartisanship.
"I'm a Democrat, I'm a progressive, I'm gonna make sure that our agenda is enacted, but I also want to listen to the Republicans, their good ideas and make sure that those, the good ones, are incorporated in our policies," Pritzker said.
WATCH: LOOK BACK AT GOV. RAUNER'S TENURE
"I think there definitely will be an end to the honeymoon period, but I believe there's a real commitment to working together, talking to Republicans and Democrats, because our problems are too big for one party to solve themselves," said State Treasurer Mike Frerichs.
Pritzker's first draft for a budget proposal is due in a month.
Meanwhile, outgoing Governor Bruce Rauner tweeted Monday morning that, "It has been a privilege to serve the people of Illinois as Governor."
It has been a privilege to serve the people of Illinois as Governor. I am so grateful for the opportunity. I pray the new administration will build on the challenges we met to conquer the challenges that remain. May our future be bright and may God bless our great state.— Governor Rauner (@GovRauner) January 14, 2019