Ann Maguire, 61, was stabbed to death by a 15-year-old pupil at Corpus Christi Catholic College in Leeds in April.
Her attacker Will Cornick, now 16, was jailed for a minimum of 20 years at Leeds Crown Court in November.
The plaque is displayed at the pavilion at Wigan's Mesnes Park where Mrs Maguire sold ice creams as a teenager.
A rose was also planted in the park's memorial garden.
The plaque was unveiled on Friday by Mrs Maguire's sisters, Shelagh Connor and Denise Courtney.
Ms Courtney told BBC Radio Manchester it was "very, very important" to have a memorial in Wigan.
She said: "This was her hometown; she was here for 19 years of her life and she still has family and friends [here].
"She said she wanted somewhere this side of the Pennines for people to go to to remember her without having to travel to Leeds."
Ms Courtney added: "She was an extraordinary person; she touched so many people in so many different ways particularly the students she taught for 40 years."
She said the words on the plaque "capture the essence of Ann and the person she was".
They say: "Ann was one of life's beautiful, sunny and extraordinary people. May her goodness, kindness and generosity of spirit continue to be an inspiration to us all and may her memory never be forgotten."
A memorial service was held in Mrs McGuire's memory on Thursday, featuring a choir consisting of many of her former pupils.
A plaque dedicated to a murdered school teacher has been unveiled in her hometown in Greater Manchester.