The Prime Minister sent her warm wishes to the new town as it marked its half century.
She made the remark while addressing a question from Telford MP Lucy Allan regarding problems in the constituency caused by unfinished new housing estates.
Mrs May said: "I understand it is Telford's 50th anniversary, so I would like to congratulate Telford on its 50th anniversary."
Ms Allan smiled and gave Mrs May a "thumbs up" sign when the Prime Minister referred to the milestone.
A number of events have been lined up for the coming year to mark the 50th anniversary of what was previously Dawley New Town being renamed Telford.
As part of the celebrations, Telford & Wrekin Council has planted 170,000 daffodils to represent each of the borough's inhabitants.
Opera singer Russell Watson, and comedians Al Murray and Dara O'Brien are among the big names lined up for a series of celebratory entertainments.
Telford took its name after the Scottish civil engineer Thomas Telford, who was Shropshire's county surveyor during the late 18th century.
He was responsible for the construction of many of the county's buildings, bridges, canals and roads.