Cllr Adam Stokes was chosen at a meeting in the Mayor’s Parlour in the Guildhall on Tuesday night.
Cllr Dean Ward was elected as the Deputy Mayor of Grantham.
Both councillors will take up their positions on 30 May at a mayor-making ceremony, when the current Mayor of Grantham, Cllr Lynda Coutts, will hand over the chain of office.
Cllr Stokes said: “I am delighted my fellow Charter Trustees have given me the opportunity to become mayor.
“I look forward to it and hope to spread the word about Grantham around the town and the district.
“It’s going to be an interesting year because I am coming in without being deputy so I am going in feet first.”
Cllr Ward, who was re-elected to represent the Grantham Arnoldfield ward last week, said: “I am excited.
“I am looking forward to the next couple of years and hoping to learn from Adam while he is mayor.”
Cllr Stokes, who is in his ninth year at South Kesteven District Council, retained his seat to represent the Grantham Springfield ward at the local elections last week.
by Tom McBeth