The former IT girl had been battling the illness since last January and passed away at her home in London earlier today.
Tara revealed her shock diagnosis last January, after revealing that she had undergone a series of blood tests the previous summer.
A police spokesman told The Sun: “Police were called by London Ambulance Service at approximately 13:40hrs on Wednesday, 8 February to an address in Bramham Gardens, SW5.
Tara Palmer-Tomkinson has died at 45 following a brain tumour
Tara Palmer-Tomkinson opens up about secret battle with brain tumour
People who died in 2017: Celebrities and famous people who have died
Tara had revealed last January that she was suffering from a brain tumour
“A woman, aged in her 40s, was pronounced dead at the scene. Next of kin have been informed.
“The death is being treated as unexplained. At this early stage, police are not treating the death as suspicious.
“Enquiries into the circumstances are ongoing. The Coroner has been informed.”
Tara was found dead at her London home earlier today
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It's claimed that doctors had discovered a malignant growth in the socialite's pituitary gland that was affecting the production of the hormone prolactin.
Opening up about the illness in November, Tara confessed: "I went to the doctor to talk about my latest blood test results when I got back from skiing in January.
"I said, 'What does it mean? Can you translate it?' And the doctor said, 'As I suspected, you have a brain tumour'."
Tara Palmer-Tomkinson was famed for her tumultuous lifestlye
The daughter of Prince Charles' close friends Charles and Patricia Palmer-Tomkinson, Tara was famed for her tumultuous lifestyle.
In the mid-nineties, the TV presenter started an eponymous weekly column for The Sunday Times and also "contributed" to numerous other publications including GQ, Tatler and The Mail on Sunday.
However, in 2002, Tara rocketed to new levels of fame after appearing on I'm A Celebrity… Get Me Out of Here!
Moments that included her being gunged in the jungle shower and boldly taking on one of the show's first ever Bushtucker Trials saw the star win over the hearts of the nation as she finished runner-up on the ITV reality series.
On the back foot of the ITV show, Tara made a string of reality TV appearances, featuring on the likes of Blind Date, Top Gear and Would I Lie to You?
Her hosting credits also include, and are not limited to, Top of the Pops, Junior Eurovision, as well as presenting stints on GMTV and LBC radio.
In 2006, Tara hit the headlines after her septum nasi collapsed, which the outspoken star admitted was down to her former £400-a-day cocaine addiction.
Previously recalling her lowest point in an interview with the Daily Mail, Tara admitted that her lowest point came when she overdose on the drug alone in her flat, leaving her unable to move for three days.
She recounted: "I wasn't a pretty sight. I'd thrown up and I was covered in burns, because I couldn't reach the ashtray so I put my cigarettes out on my hand. If you use a lot of coke, it makes you very numb, so I used to blister myself when I got in a hot bath because I couldn't feel it.
"And my flat was just very, very unhygienic. There was make-up all over the kitchen and the dishwasher had stagnant water in it."
Tara revealed last year that doctors had told her she had a brain tumour
Tara later underwent cosmetic surgery to have her septum rebuilt, reportedly at a cost of £6,000.
The British socialite remained fairly under the radar until 2014, when she once again caught attention after being arrested at Heathrow airport.
Despite reports claiming that Tara had launched into an angry tirade on staff after being refused access to a first-class lounge, she claimed it was merely a panic attack that triggered her meltdown.
She told The Sun at the time: "I was on my own reading a magazine. I felt people behind me taking pictures. I could hear them all talking about me and laughing about me and I got upset.
"It's nothing to do with the lounge, I swear on the Bible. I got upset with the man saying, 'You are not fit to travel, you are crying'. I really lost my temper."