The local authority has pumped £1.3m into the project, which has seen the land on Pye Green Road transformed.
The ribbon was cut by Cannock Chase District Council leader George Adamson. The opening comes three years after work began.
The site now features a new adventure play area, a BMX track, footpaths and cycle-ways, community allotments and an outdoor gym.
During yesterday’s ceremony, Councillor Adamson said: “It’s been vital to keep this site open as it’s the most deprived area of Cannock with the most health problems and we wanted to reverse the decision to build houses here.
“We wanted it as an open space so people can get fit and enjoy themselves. It’s great for young people.
“We consulted all the schools and we put here what they said they wanted.
“The BMX track is amazingly popular with children in the area and we hope that continues.
“It’s going some way to putting right mistakes of councils in the past.”
The site also has improved safety and security, with new lighting, fencing and gates and CCTV surveillance.
The work was completed by construction company Blakedown Sports and Play Limited.
Christine Mitchell, the council’s culture chief, said: “It’s been a lot of hard work but we have achieved our aims.
“This is only phase one and if we can get the funds we want to do phase two and put a community building and changing rooms here. Everything has worked well and the facilities are being used.
“We hope the Friends of Cannock Stadium Park group will take off and help us keep the space in this condition.
“I was a part of the Save Our Stadium group and we fought against the housing development and managed to keep it for a public open space so I’m happy.” Joe Taylor, founder of the Friends group, said: “We set up this group to keep the
park as a clean, tidy and safe place for families to use.
“We have a community set up now and it’s going at some pace. Keeping this safe and clean will invite people to come and deter anti-social behaviour.”
Council bosses approved plans for the stadium revamp in 2014 – announcing that the first work would begin on the site the following year.
It has been empty since 2008 when it closed, forcing groups to move elsewhere for sports facilities.
Plans were scrapped in 2012 for the site to be turned into residential homes.