The actress and comedienne, who starred as long-suffering housewife Zainab Masood, is leaving the soap after five years.
Her character arrived in Albert Square with daughter Shabnam in 2007 as the new owner of the post office. She was later joined by husband Masood and her two sons.
Wadia said: "Playing Zainab has been a gift and a privilege.
"I'll always be hugely proud of the talented friends I've worked with and I'm so grateful for the special bond with our audience who watch, care and talk to us every day. We're a family of millions.
"Letting go of something you love is never easy but the time has come to move on and every ending brings a new beginning. Here's to future loves."
During her five years on the show, Zainab has accepted her gay son and endured her ex-husband drugging her and then dying in a house fire.
Wadia won 'Best Comedy Performance' and 'Best Partnership' at the 2009 British Soap Awards with Nitin Ganatra, who plays her husband Masood.
The Masood family has been rocked in recent months by the departure of Zainab's son Syed, who left with husband Christian Clarke.
It has been reported that Zainab is not expected to be killed off.
EastEnders boss Lorraine Newman said of Wadia's soap legacy: "For the past five years Nina has brought to life the wonderful Zainab - the formidable, fun- loving, opinionated, fiercely competitive matriarch.
"Nina's range as an actor is quite exceptional, from her comedic double acts right through to her ability to pull on our heart strings with incredibly moving drama.
"We are very sad to be losing Nina and wish her well in ventures new. She will be missed by the production as much as the audience."