The 24.1 billion forints (EUR 80m) contract for the initial work is planned to be signed by the beginning of September.
Strabag Építőipari Zrt has won the public procurement competition to renovate the northern section of the line which encompasses six stations.
A new competition is to be launched for the contract to renew the central and southern sections.
During the work on the northern section, the metro will function between Kőbánya-Kispest and Lehel Square, the Budapest transport authority BKK told the paper.
In the meantime, the replacement buses are being stocked and traffic changes are prepared for their implementation, the paper said.