The former Spurs captain was joined by students and staff to open the facility at Onslow St Audrey’s, which has been 10 years in the making.
"It’s a pleasure for me to be here to open up the new pitch. I hope it gets many years of great use," said King - who made more than 320 appearances for Tottenham and played 21 times for England.
"I’d have loved something like this back in my day."
The Old Rectory Drive school has been collaborating with the Premier League club since September 2024, with King joining students in getting a feel for the new pitch.
The partnership with Tottenham provides learners at Onslow St Audrey's with insight and experience into coaching, helps further develop and supports elite sports performance.
Headteacher Julie Jones was delighted to see the project completed after a decade-long wait: adding: "This project has been a decade in the making, and it is a testament to the vision, hard work, and dedication of our school community and collaborative working with Danes Educational Trust.
"We are proud to offer our students world-class facilities to nurture their talents and foster a lifelong passion for health and fitness.
"Today, we celebrate not just a new pitch but a new chapter for OSA."
Danes Educational Trust chief operating officer, Dominic Richards added: "The improved sporting facilities and classrooms have been a vision of the school since 2012 and these excellent spaces will benefit current and future generations of learners.
"The all-weather football pitch is the crowning jewel in a series of investments that have redefined the school’s physical education facilities, alongside a state-of-the-art sports hall and fantastic dance studio.
"Together, these facilities represent a significant leap forward in their mission to become the number one choice for secondary physical education."
Work to improve the sports facilities at Onslow St Audrey's also took a big step back in October last year, when a new 'state-of-the-art' sports hall was opened.