Walker emerged from the fight as a hero to Republicans nationwide, but a villain to unions and Democrats who responded by collecting more than 900,000 signatures to put Walker back on the ballot less than two years into his four-year term.
"We know that the real battle is ahead, and it's really going to be a battle for the values of Wisconsin," Barrett said shortly after the race was called. "Our view is Scott Walker has done a lot of damage to the state, and Wisconsin can't be fixed as long as Scott Walker is governor."
Walker's deputy campaign manager Dan Blum issued a statement saying Barrett was about to enter his "third statewide losing campaign." Barrett also ran for governor in 2002 and lost in the Democratic primary.
"Rather than Tom Barrett's path of taking Wisconsin back to the days of billion-dollar deficits, double-digit tax increases and record job loss, we are confident that voters will choose to stand with Governor Walker and move Wisconsin forward," Blum said.
Based on preliminary results, Barrett got 55 percent of the vote in the Democratic primary. Former Dane County Executive Kathleen Falk, who was the favored candidate of the unions that pushed the recall, came in second with 37 percent.
Union leaders said they were ready to quickly pivot and build support for Barrett.
"I think we'll get just as much activism," said AFL-CIO national political director Mike Podhorzer. "This isn't about 'Are we for team A or team B,' this is about what workers need. And workers understand they are being hurt by Walker."
Barrett has had a rocky relationship with unions over the years, and some Wisconsin union leaders urged him not to get into the recall race. He has promised to work toward restoring collective bargaining rights Walker took away, but he didn't go as far as Falk, who pledged to veto any state budget that didn't undo Walker's changes.
Still, numerous unions that had backed Falk - including the statewide teachers union and the largest state employee union - issued statements praising Barrett and pledging their support.
Other Democrats on the ballot finished far behind. State Sen. Kathleen Vinehout got 4 percent while Secretary of State Doug La Follette trailed with 3 percent. Gladys Huber, the fake Democrat, got less than 1 percent.
Walker easily defeated Arthur Kohl-Riggs, a Walker foe running as a Republican.