The new arrival, played by actress Gemma Oaten, is defensive, argumentative and insistent on defending her young niece Amelia (to be played by 7-year-old Daisy Campbell), after she is accused of bullying Samson Dingle.
The 27-year-old previously appeared in BBC1's Doctors and has been in various stage productions at Drama Studio London.
Pictured: Gemma Oaten as Rachel Breckle.
Oaten said: "I'm thrilled to be joining Emmerdale. I've always watched the show and getting the part of Rachel is a dream come true. She is a fantastic character and I'm so excited about filming my first scenes."
Series producer Stuart Blackburn added: "I'm delighted to welcome Gemma to the cast. Rachel will certainly ruffle a few feathers with her straight-talking approach but beneath the surface she is fiercely loyal with a hidden heart of gold."
Oaten starts filming this month and viewers will see her arrival on screen in late July.
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