The Duke of Cambridge was at BAE Systems' shipyard in Govan on Tuesday to carry out the official task and meet apprentices and graduates in training.
Based on the River Clyde in Glasgow, BAE is designing and manufacturing warships for the Royal Navy's surface fleet.
The Type 26 frigates will be part of the Carrier Strike Group, replacing the submarine-hunting Type 23s from the mid-2020s.
The Type 26 programme secures more than 4,000 jobs across BAE Systems and the wider UK maritime supply chain, providing a strong foundation for shipbuilding at the company's Scottish facilities into the 2030s.
His Royal Highness was taken on a tour of HMS Glasgow by an electrical apprentice, to see how the ship's construction is progressing.
Prince William spoke with some of BAE Systems' apprentices and graduates in training, who are honing their skills working on advanced technology programmes.
Prince William then delivered a short speech, before officially cutting Belfast's first plate of steel.
He said: "The scale of achievement is truly staggering, and all the staff I've met here today are rightly proud of what you are doing.
"Proud, not just because you are creating these cutting-edge ships, but because you are supporting the Royal Navy and the national security of the United Kingdom."
During his speech, the Duke of Cambridge announced that the Queen has approved the appointment of the Duchess of Cambridge as sponsor of HMS Glasgow.
A ship's sponsor is a long-standing tradition in the Royal Navy and other recent sponsors of Royal Navy ships include the Queen and the Duchess of Cornwall.
A sponsor is chosen to have a strong and enduring personal connection to the vessel and her crew, often supporting milestones, events and deployments involving the ship.