Pallett was born and brought up in Carlisle, Cumbria by her English mother and grandmother. Her maternal-grandfather was Italian, and her mother and Iranian father separated before she was born.
Educated at Robert Ferguson Primary School and Trinity School, she then graduated with a BA Honours degree in Media and Cultural Studies from Liverpool John Moores University. Pallett studied at the Manchester School of Screen Acting on weekends, and began auditioning outside her studies.
In her last year at university, Pallett co-formed girl band Urban Angel, writing songs for them with production and management by ex-East 17 member and Ivor Novello award winner Tony Mortimer. After landing a deal with a record label, Pallett spent a year developing her music.
In 2005, Pallett auditioned for the role of Delilah Dingle in Emmerdale. After some final callbacks and workshop based auditions, the producers asked her to play the feistier role of Jo Stiles, a role they were still writing. Pallett won critical acclaim for her major domestic violence storyline in 2008-2009. In August 2008, Pallett became the public face of the Early Warning Signs campaign for UK domestic violence charity Refuge, that urges young women to look out for early signs where a partner may turn violent in a relationship. During her 130 shows and three years on Emmerdale, Pallett was nominated for several awards as Sexiest Female, Best Storyline, and Best Actress at The British Soap Awards 2007, 2008, 2009, the Inside Soap Awards, and TV Quick Awards 2008.
In November 2005, Pallett won Celebrity Stars In Their Eyes as Gloria Estefan. In January 2006, she appeared in the ITV reality singing show Soapstar Superstar, finishing fourth in January 2006, and raising over £70.000 for her supported charity the Eden Valley Hospice Jigsaw Appeal. Pallett has had several front covers and modelling features in Closer, Reveal, Now, Sugar, Mizz, Hello and OK magazines. Pallett regularly topped the 'sexiest' poll awards in lads mags, including photoshoots for Loaded and Maxim, where she fronted both international covers (July 2008 and May 2009).
After leaving Emmerdale, Pallett took part in the fourth series of ITV's Dancing On Ice, which began on 11 January 2009 with professional partner Daniel Whiston; the couple made headlines for the risque move The Headbanger. Pallett then went on the Dancing on Ice Bolero Anniversary UK Tour 2009. Scheduled to play the lead role in 2009 Christmas pantomime Cinderella at the Theatre Royal, Newcastle upon Tyne, she pulled out after 3 weeks of starting performances following the sudden death of her best friend.
In 2010, Pallett took roles in the film Lake Placid 3, her Hollywood debut, and filmed a guest role for the BBC's Casualty. She was one of the singers in the UK production of the musical Rock Around The Clock, making her professional stage debut, which toured the country until September 2010. She then filmed a role in the British production Billy, playing WPC Hannah Reed opposite Sean Pertwee.
In September 2010, Pallett toured with Eve Ensler's famous stage show Vagina Monologues, opposite Nikki Sanderson and Sue Jenkins. Pallett won rave reviews having starred as the female lead (Teena Satin) in the rep theatre run of Satin 'N' Steel at the Oldham Coliseum Theatre, from 14 April through 7 May 2010, directed by Joyce Branagh. The two hander play also starred Matt Healy.
In 2011, Pallett appeared in an episode of The Real Hustle. In 2012 Pallett appeared as Shelby Dixon, a pupil in the BBC series Waterloo Road, and has most recently appeared in Casualty as Keeley Hyatt. Pallett is currently shooting British film 'Devil's Tower', playing the lead role of Sarah, opposite Jason Mewes and Francis Ruffelle.
In January 2014, Pallett revealed she had discovered a mark on her left breast the previous year, and had been diagnosed with a rare form of skin cancer, but had now been given the all-clear.