The 10-year contract is for estates and facilities management and Landscape Group is part of a joint venture led by Balfour Beatty Workplace.
Landscape Group will manage the park and tackle biodiversity, all aspects of horticulture and cleansing and everything outdoors.
The park is the size of 357 football pitches and includes sculpted landforms, thousands of trees, wildflower meadows, 500,000 wetland plants and over 8km of waterways.
Olympic Park Legacy Company made the announcement with prime minister David Cameron on Monday.
• For the full story see the 16 January issue of Horticulture Week.