It is the first time that Wyndham, Queen Elizabeth and Dysart parks have each been awarded coveted Green Flag status in the same year.
The Cabinet Member for Culture and Visitor Economy, Cllr Rosemary Trollope-Bellew, said: "These awards celebrate the hard work and dedication of everyone involved in looking after the parks, including the many volunteers who contribute so much.
"Green Flag status is a mark of excellence for parks and green spaces in England and Wales and it only goes to the best in the country, so for all three of Grantham's parks to have made the grade in the same year is a fantastic achievement."
It is the first ever Green Flag Award for Dysart Park, while Queen Elizabeth has maintained the standard for a second year.
The Dysart Park site was given to the people of Grantham in 1908 by Sir Lionel William John Manners, late Earl of Dysart. In his will he gave precise instructions that the land should be used for recreation purposes only.
The 25-acre Queen Elizabeth Park was established in 1980 to mark the 80th birthday of Queen Elizabeth the Queen Mother and is popular with dog walkers, joggers and cyclists.
Wyndham Park, where a £1million restoration to its former glory as a World War One memorial park was completed in 2018, receives its 11th consecutive award and has also retained Green Heritage Site accreditation for a third year in recognition of effective management of its historic features.
The Green Flag scheme, managed by environmental charity Keep Britain Tidy, under licence from the Ministry of Housing Communities and Local Government, sets the benchmark for the management of recreational outdoor space in the UK and around the world.
SKDC's Cabinet member for People and Safer Communities, Cllr Annie Mason, said: "When a Green Flag flies it shows that an area is maintained to the highest of standards.
"Our parks are extremely popular and so important for our mental wellbeing. These awards are an acknowledgement of all the hard work that goes into maintaining them."
Keep Britain Tidy's Accreditation Manager Paul Todd said: "I would like to congratulate everyone involved in making these parks worthy of Green Flag Awards. They are testament to the work of staff and volunteers who do so much to ensure they maintain the high standards demanded by the awards."