Since taking over in October 2006, Santer has pioneered EastEnders through some of its most powerful and controversial storylines of recent years, including the Tony/Whitney paedophile plot, Danielle's death and Stacey's bipolar.
His time in office has also seen the return of a handful of the soap's iconic characters, such as Ricky Butcher (Sid Owen), Bianca Jackson (Patsy Palmer), the original Sam Mitchell (Danniella Westbrook) and from early next year, the rest of the Jackson clan, including Carol, Sonia, Robbie and Billy.
Santer also introduced the show's most successful Asian family the Masoods into Walford and spearheaded the Bradley/Stacey/Max Christmas day reveal, which was seen by an average of 14.38m viewers. He also took the decision to mark the show's 25th anniversary with a special live episode.
Santer (pictured below) said of his departure: "I've had the most fantastic time at EastEnders. It's without doubt the best job in telly, and I've loved every minute of it. It's a busy and challenging job so I'm now looking forward to becoming reacquainted with my family and friends. I'm grateful to all the people I've collaborated with over the last three years who work so hard and so creatively. It's been a real pleasure to work with them and to get to know them, and I'm going to miss them all enormously."
From February 20, Santer will relinquish his role to ex-Hollyoaks producer Bryan Kirkwood, who helmed the Channel 4 teen soap for three years before stepping aside to make way for successor Lucy Allan.
Kirkwood headed up production of E4's late-night Hollyoaks offering Later, which featured soapland's first parachute death and a cameo performance by Welsh songstress Bonnie Tyler.
Prior to Hollyoaks, he spent a decade working at Coronation Street as a storyliner during the Richard 'Tricky Dicky' Hillman (Brian Capron) era.
Santer added of his successor: "I'm delighted that I'm passing the show on to Bryan Kirkwood. He's a vastly talented and original producer with a brilliant storylining mind. I'm confident that under him, EastEnders will continue to thrive and to grow and to keep delivering the very best drama to its massive audience."
Controller of BBC drama John Yorke said: "Diederick has presided over an incredibly strong period in the show's history and demonstrated an instinctive mastery of what makes the programme such a success. Able to switch from brave and radical public service storytelling to big sweeping set pieces, he has been concerned only to get the best out of those around him and to match the highest standards of the programme's founders."
He went on: "Leaving EastEnders fighting fit and at the top of its game as it reaches its quarter century, he'll be missed hugely by cast and crew. He's going to be a very hard to act to follow but I'm confident Bryan is the right man for the job."
Santer will continue to executive produce for the BBC in a special position tasked to develop "new shows that can be internally co-produced". The dramas will be created through a joint venture with BBC Drama Production and BBC WorldWide Los Angeles.