Dubai-based Sidara will design and supervise construction of new city in Bishoftu.
The deal paves the way for Kenya's first waste-to-energy plant.
The 84 km road was scheduled for completion in December 2022.
The project stalled after China decided not to provide additional loans.
The proposed factory will be located in Mwingi Central, Kitui County.
The solar photovoltaic (PV) plant will be set on 80 hectares of land.
The Sh175 billion project is expected to get underway this year.
The cost of the project is now $6.4 billion, up from $5.7 billion.
The roads forms part of the Mombasa–Kampala–Kigali expressway.
Work for the country’s first research reactor set to kick off in 2026.