Lee secured his bid during Tuesday's election against Democratic former Nashville Mayor Karl Dean.
"I'm grateful for the voters of Tennessee, grateful that you placed your trust in us to lead this great state," Lee said during his acceptance speech in Franklin, in front of hundreds of supporters. "We ran a positive campaign from the very beginning until the very last day because we wanted to give a picture of what this state could look like."
Lee cast himself as a political outsider who faced the death of his first wife of 16 years, Carol Ann, from a tragic horseback riding accident and made a personal transformation. His religious faith became a defining characteristic along the campaign trail. He described running for the governor's office as a "calling."
His campaign remained overwhelmingly positive, but he has faced criticism for not providing specific details on key policy positions.
As his Democratic opponent campaigned heavily on the need to expand Tennessee's Medicaid eligibility to improve health care access across the state, Lee steadfastly opposed the plan.
Instead, Lee promised to work to fix the state's health care system, calling it a long-term project that may take 15-20 years. However, unlike Dean, the Republican says he would ultimately lobby the Tennessee Legislature to vote against Medicaid expansion, should lawmakers ever get close to doing so.
Lee also says he supports school choice, a position his opponents say will result in public funds being funneled toward private schools. He hasn't offered details about what policy options he'll rule out as governor.
Lee serves as chairman of his family business, Lee Company, a $225 million mechanical contracting, facilities and home services firm with more than 1,200 employees. Lee also is active in his 1,000-acre family cattle operation.
"Bill Lee is a man with strong character and love for our state and will make the right decisions to keep Tennessee moving forward," Haslam said in a statement. "I am excited to see what this state will accomplish under his leadership."
As of 8:15 p.m. CDT, Dean had not conceded.
"I want to speak just a minute to those who may not have voted for me - I want them to know from the bottom of my heart I care about you and I care about your families," Lee said. "I want you to ultimately be proud that I am your governor
Voters who backed Lee said his campaign style stood out
"Bill didn't go onto the attack," said Sandi Wells, 62, who voted for Lee in Williamson County. "He just talked issues with people. And that's what I think we want."
Wells leads a weekly coffee gathering in which politics is discussed in Williamson County, the upscale Nashville suburb and Republican stronghold. She said she has watched grow as a candidate since the primary and described Lee had a "very warm vibe to him."