Yes. Under ORC 3723.02, a company doing radon mitigation needs an Ohio Department of Health mitigation contractor license, the person supervising on site needs a mitigation specialist license, and anyone testing for others needs a tester or specialist license.
More detail
ODH's Radon Education and Licensing Program, headquartered on North High Street in Columbus, licenses mitigation contractors, mitigation specialists, radon testers, radon labs, and training providers. Its Hire a Professional page links a licensure map for finding testers and mitigation contractors near you. Specialist licenses run two years, with 16 hours of continuing education in that span, 8 of them on mitigation. Out-of-state licensees may work in Ohio up to 90 days a year, and only after notifying ODH. National credentials such as NRPP are useful, but the Ohio license is the legal requirement. Every Ohio proposal must list the license numbers of the specialist and the contractor, and licensees report each job's before and after results to ODH every quarter. All mitigation contractors you work with here hold the Ohio license. See how to check a license.