The 38-year-old actress shared the news with the Sunday Mirror and said she feels "like the luckiest woman in the world".
The Emmerdale star will welcome her first child with husband Jason Carrion in the autumn in New York City, where she lives.
She told the paper: “To have such a beautiful life here and be blessed with the most incredible husband and our little baba on the way… my mum’s already knitting for England.”
Ms Pallett married her firefighter fiancé Jason in New York in 2019, just two months after getting engaged.
The pair tied the knot in a small ceremony in front of 10 close friends and family.
Ms Pallett portrayed Jo Stiles on Emmerdale from 2005 to 2008 and later starred in Casualty and Waterloo Road.
The happy news comes three years after her controversial stint on Big Brother.
In 2018, she took part in the 22nd series of the reality show where she sparked backlash after wrongfully accusing fellow housemate Ryan Thomas of “repeatedly, intentionally and aggressively” punching her on the show.
Mr Thomas had been filmed playfully sparring around her, appearing to tap her on the waist at the time.
She has since stepped away from a life in the spotlight, and expressed her excitement over her pregnancy, telling the Sunday Mirror that she now knows “what happy ever after feels like”.
“My husband is driving round at all hours getting me pizza and cookies. We’re in a bubble of excitement,” she said.