Portland Park was donated to the people of Kirkby by the 6th Duke of Portland as a series of gifts dating from 1910. A small area of what is now the park was leased to Kirkby Urban Council from this date and in 1914 the Duke and Duchess of Portland celebrated their Silver Wedding Anniversary and the 21st birthday of their son, William Arthur Henry Cavendish-Bentinck, (7th Duke of Portland) by gifting the remainder of the land. The Council developed 'Portland Park' as a formal recreational area for local people and the park was a popular rendezvous on a Sunday, for church services, family walks and picnics, listening to the bands in concert, tennis and playing on the swings. Other features included formal gardens, paddling pools (now ponds) and a bowling green. The main pond known as Victoria Lake, named after the Duke and Duchess’s daughter Lady Victoria Alexandrina Violet Cavendish-Bentinck, was created in 1914 as part of the original development of the park as a formal pleasure ground.
Up until the 1960's all the paths within the park crossed over or under railway bridges. The main pathway to the west of the park was originally an embankment built to carry the first railway within the district, which was one of the first pre-steam railways in the country. The railway lines were built to serve the former local coal mining industry and the majority are now disused.
A shortage of staff after the Second World War led to less intensive management and areas of the park became less formal. Over time all of the more formal features of the park were removed, such as the bandstand, bowling green and play area. Following designation of the park as a Site of Special Scientific Interest in 1974, the park was transformed over time into a country park.
The park will eventually extend into an additional area of land known locally as the ‘Humps and Hollows’ up to the edge of the Robin Hood Railway cutting following the completion of the adjacent housing development. This transfer of land from the developer to the Council forms a condition of the planning permission to build the housing development.