Schewel, 70, said he "struggled mightily" with the decision.
Schewel was elected mayor in 2017. Before that he spent six years on the Durham City Council. He was first elected to the city council in 2011, prior to that he was on the Board of Education for Durham Public Schools.
WATCH: Mayor Schewel's full announcement
Schewel is speaking outside City Hall. He said he has a granddaughter on the way and that was a factor in his decision. He also felt the city was in "good hands" and he leaves with confidence. He said he will continue to live in Durham -- which he described as a "rough-and-tumble political town" -- and do what he can to help the next mayor.
"I did my best to make wise decisions," Schewel said of guiding the city through the pandemic. Durham is at its lowest percent positive rate since the start of the pandemic.
He added that vaccine equity is still a challenge in Durham, where minorities continue to be vaccinated at lower rates.
He said affordable housing, crime and policing and environmental challenges face the city. One of the biggest upcoming decisions will be hiring a police chief.
Asked what he described as the main two challenges, Schewel responded that gun violence and gentrification.
"We're not going to stop gun violence" until there are better gun laws, Schewel said. He added that root causes also need to be addressed.
Schewel said he'll continue to work on those issues in his remaining six months as mayor.
The mayor thanked his wife, becoming emotional as he spoke. He also thanked the people of Durham "for giving me this privilege."