Secretary of State Nellie Gorbea administered the oath of office to McKee, 69, a Democrat who was in his second term as lieutenant governor in the nation’s smallest state.
McKee ascended to the governorship shortly after his predecessor, Gina Raimondo, after her nomination to become President Biden's commerce secretary was confirmed by the U.S. Senate in an 84-15 vote.
"I have the utmost confidence in you. You are a proud Rhode Islander, a dedicated public servant, an experienced executive and a good man. You will serve our state honorably as its 76th governor," Raimondo wrote in a letter of resignation that was delivered to McKee.
Earlier Tuesday, U.S. Sen. Ted Cruz, R-Texas, had put a hold on Raimondo's confirmation, saying he believed Raimondo had not taken a harsh enough stance against Chinese telecom giant Huawei.
After taking the oath of office, McKee signed an executive order that reportedly echoed the promises made by his predecessors, which he said bound his administration "to the highest ethical standards," reports said.
McKee is now tasked with putting together Rhode Island’s state budget as well as handling the coronavirus pandemic which -- according to data from Johns Hopkins University -- has killed more than 2,500 people in his state, WPRI-TV reported.
Last month, McKee announced the creation of a new panel to guide his incoming administration's response to the outbreak. After leaving the Statehouse, McKee told reporters his immediate focus will be on vaccine distribution, according to the station.
"I just had a few meetings upstairs on vaccination and getting the teachers vaccinated," McKee said before he got into a car driven by Rhode Island State Police.
McKee's political career started in Cumberland, R.I., where he was elected to the town council in 1992. He would later go on to serve as mayor for 11 non-consecutive years beginning in 2000 when he beat incumbent Francis Gaschen, according to WPRI-TV.
Despite losing his bid for re-election in 2004 to David Iwuc, he won the office back in 2006 and held on to it until he was elected lieutenant governor in 2014.
In 2014, McKee beat out Ralph Mollis and state Rep. Frank Ferri in a three-way Democratic primary before he defeated Republican nominee, Catherine Taylor, in the general election.
Four years later, he faced off against progressive Democrat Rep. Aaron Regunberg, who secured the endorsement of Sen. Bernie Sanders, I-Vt. McKee won by roughly 2,500 votes.
McKee is described as being less liberal than Raimondo and is likely to fight for small business interests and charter school education.
"You’re going to see a little more moderate administration than the Raimondo administration," WPRI-TV political analyst Joe Fleming said. "At the same time, I don’t think it’ll be too conservative. He’s looking ahead to 2022 and being the active governor puts him in a good position. If he goes too conservative it could hurt him."
His support for charter schools resulted in him butting heads with the state’s largest public-sector unions over the years.
Fleming said improving his relationship with the unions could go a long way toward helping his chances of getting elected in 2022 -- as thousands of members are now part of his workforce, according to the station.
"It gives him something to work on over these two years – to try and mend some fences," Fleming said.
McKee will also be tasked with nominating the next lieutenant governor, who must be approved by the state Senate.
"We are ready to help the people of the state of R.I. in this pandemic and beyond that," he said, according to the Providence Journal.
The Associated Press contributed to this report