The actress, best known for playing Walford's Sam Mitchell, will feature in an upcoming storyline with the Channel 4 soap's McQueen family.
Westbrook's character Trudy will be seen on screen from February when she hires cash-strapped Jacqui (Claire Cooper) and Theresa (Jorgie Porter) as cleaners.
While exact details of the subsequent story have yet to be disclosed, viewers will see that Trudy shares a history with Jacqui as the characters were previously in prison together.
Westbrook is already friends with Hollyoaks co-star Kieron Richardson (Ste Hay) after they both competed on the 2010 series of ITV1's Dancing on Ice.
Hollyoaks airs weeknights on Channel 4, with first look screenings on E4.