With 94% of the vote reporting on Wednesday morning, Johnson had 51% of the vote, followed by Barnes with 49%.
Johnson was viewed by race observers and assessments like FiveThirtyEight as one of the most vulnerable GOP lawmakers on the ballot this cycle after the battleground state flipped for Joe Biden in 2020.
"Truth has prevailed over lies and the politics of personal destruction," he said in a statement on Wednesday morning. "I want to thank my family and everyone who supported me and worked so hard to save this U.S. Senate seat. I will do everything I can to help make things better for Wisconsinites and to heal and unify our country."
The Republican senator was first elected in 2010 and is serving his second term in Congress, sitting on committees including foreign relations. Barnes is the first Black lieutenant governor in Wisconsin and would have been the state's first Black U.S. senator had he won.
Johnson, like others in his party, focused heavily on crime and the economy while on the campaign trail, pushing to label Barnes as a far-left politician who was soft on public safety and wanted to "abolish" some federal law enforcement, charges which Barnes denied.
"Are you better off or worse off since Democrats took control?" Johnson asked during the last debate.
"The dispiriting nature of attempting to cut or use the code words of 'reallocate,' 'over bloated budgets' -- my opponent says that it pains him to see a fully funded police budget. I mean, that type of rhetoric," Johnson said. "Those types of policies are very dispiriting for police."
Barnes, while supportive of redirecting police funding, has insisted that he doesn't support defunding the police.
Barnes also argued Johnson's statements were hypocritical given Johnson's reaction to the Jan. 6 attack at the U.S. Capitol. Johnson claimed he strongly denounced the violence, despite once saying "it didn't seem like an insurrection to me."Also under scrutiny in the race were Johnson's comments about Social Security. The senator's proposed making funding for Social Security and Medicare discretionary, rather than mandatory.
Johnson said wanted to financially rescue the entitlement programs, while Democrats have argued that could lead to their elimination entirely. Biden repeatedly lambasted Johnson's plan on the campaign trail as he pitched the election as a choice between Democrats and extremist "MAGA Republicans."
"I never said I wanted to cut or put Social Security on the chopping block," Johnson said during the final debate with Barnes.
The Senate is currently split 50-50, with Democrats in control because Vice President Kamala Harris cannot break ties. ABC News has not yet projected control of the upper chamber after Tuesday's midterm elections.
ABC News' Oren Oppenheim and Paulina Tam contributed to this report.
Ron Johnson projected to win reelection, defeat Mandela Barnes in Wisconsin originally appeared on abcnews.go.com