The company’s 300 contract hire vehicles will be managed on a fully outsourced basis.
Howard Churchill, of Otto said: “We decided to appoint Zenith because it has an innovative and flexible approach to fleet management, and a reputation for delivering what it promises.
"This minimises the administrative burden for companies such as ours.”
Philip Jerome, Zenith’s new business sales director, said: “Otto is a highly-regarded company with a reputation for quality and service, so we are delighted to be chosen as its fleet provider.
"The fact that our businesses are based so close to each other makes the appointment even more pleasing.”