The project took place on Brynglas Road and was carried out by Wales & West Utilities in partnership with Newport City Council.
The scheme began in January and forms part of ongoing work to maintain and future-proof the gas network.
Andrew Coleman, who managed the upgrade for Wales & West Utilities, said: “We’d like to thank the local community and commuters for bearing with us whilst we completed this essential work.
“While most of the gas network is underground and out of sight, it plays a central role in the daily lives of people across the area.
“Whether it’s heating your home, making the family dinner or having a hot bath, we understand how important it is for your gas supply to be safe and reliable and there when you need it.
“This work was essential to keep the gas flowing to local homes and businesses today, and to make sure the gas network is ready to transport hydrogen and biomethane, so we can all play our part in a green future.”
Wales & West Utilities operates the gas emergency and pipeline service for Wales and the south west of England.
The company reminds residents to call 0800 111 999 immediately if they smell gas or suspect carbon monoxide.
Engineers are available 24 hours a day to respond to emergencies and ensure public safety.