Missouri voters guaranteed themselves paid sick leave and inflation bumps to the minimum wage. The governor just repealed them.

Eight months after voters approved it, Missouri Gov. Mike Kehoe signed the repeal of a law Thursday that had guaranteed paid sick leave to workers and inflationary adjustments to the minimum wage.

The move marked a major victory for the state’s largest business group and a frustrating defeat for workers’ rights advocates, who had spent years — and millions of dollars — building support for the successful ballot measure. The repeal will take effect Aug. 28.

Kehoe, who also signed a package of tax breaks Thursday...