The daughter of Ian Beale - played by Hetti Bywater - will be murdered in a storyline set to leave viewers guessing the identity of the killer.
The culprit will not be revealed until next February when the soap celebrates its 30th anniversary.
Bywater is the fourth actress to play the character since her birth in 1993.
She has been on the BBC One soap in her current incarnation since 2012, replacing Melissa Suffield who starred as the character from 2004-10.
Casey Anne Rothery and Eva Brittin-Snell also played Beale in her younger years.
The soap's executive producer, Dominic Treadwell-Collins, said last year the Beale family would become embroiled in a major plot.
He added Lucy's death would give actor Adam Woodyatt - who plays the soap's only remaining original character Ian Beale - "a chance to shine".
Beale will be left questioning how much he knew about his daughter as he discovers various secrets following her demise.
EastEnders' last "whodunit" was in 2009 when Archie Mitchell, played by Larry Lamb, was murdered by an unseen person on Christmas Day.
The killer was revealed to be Stacey Branning during a live episode broadcast in February 2010 to mark the soap's 25th anniversary.
Audiences were also hooked in 2001 when Phil Mitchell was shot outside his Walford home.
Some 22 million viewers subsequently tuned in to find out that his ex-girlfriend Lisa was the shooter.
EastEnders character Lucy Beale is to be killed off this Easter, the BBC has confirmed.