The development will also include a new timber building housing a café and cycle shop and a large outdoor seating area, with views across the lake. The existing car park will be extended to offer an additional 28 spaces, including nine disabled spaces. Building works are anticipated to begin in March 2017.
The Parks Trust Milton Keynes and Golf City MK have partnered on the project.
Chief executive of The Parks Trust David Foster said: "Our visitor surveys always tell us how much people enjoy visiting Furzton Lake but that they wish there were toilets, café and activities for children.
"This development will give residents of Milton Keynes greater opportunities to spend time with friends and family in an outdoor environment as part of a healthy lifestyle.
"The proposed facilities have been designed specifically for this project and are unique in the UK. They will conform to the highest design in terms of appearance, safety and security."
The Parks Trust is also investing just over £4m over three years in Willen Lake, where a children’s splash park, landscaping works, an expanded car park and new catering and toilet facilities.
New Willen Lake general manager Rob Wood told Horticulture Week that the ambition was for these and other planned improvements to grow visitor numbers by 50 per cent to one and a half million visits a year.