The Oscar-winning actor and director, 94, confirmed the tragic news in a heartbreaking statement on Thursday.
The pair had been in a relationship since 2014.
Eastwood said: ‘Christina was a lovely, caring woman, and I will miss her very much.’
A Warner Bros. spokesperson told THR that no further information would be forthcoming on Christina’s death as Eastwood grieves the loss privately.
Eastwood and Sandera met when she worked as a restaurant hostess at Eastwood’s hotel, the Mission Ranch, in Carmel, California in 2014.
Despite their 33-year age-gap, their romance quickly blossomed.
Little was publicly known about their relationship but she did support Eastwood at various film premieres and awards shows.
She made her red carpet debut with the star at the 2015 Oscars where his drama American Sniper was up for six awards.
Sandera was first photographed with Eastwood in June 2014 with insiders saying she had moved into the $20million mansion he had built for ex Dina months earlier.
They were last seen publicly together in 2019 – with the pair posing in November 2022 with Clint’s daughters in a final social media snap.
The same insider told an entertainment magazine that Eastwood was ‘with Christina and happy’.
‘Clint’s kids have all met Christina and like her,’ said the source, who added that the children all thought she was ‘normal’.
The pair began dating a year after Eastwood divorced second wife Dina after 17 years of marriage.
Sandera was previously married to Paul Wainscoat in 2003 for just 11 months – and the former couple had a turbulent union which resulted in Sandera being arrested for domestic battery.
Wainscoat told The National Enquirer in 2015 that on July 17, 2002, just two months after he began dating Sandera, she became enraged when he refused to move in with her, and when he tried to leave ‘grabbed onto his shirt and scratched his neck to prevent him.’
He managed to call the police, who in their report, noted a ‘strong odor’ of alcohol on Sandera’s breath as they arrested her for domestic battery.
The couple still married eight months later though, after, according to Wainscoat, he spent $80,000 on the couple’s honeymoon and jewelry and ‘dental work’ for his bride.
A few months after they married another physical fight broke out between the pair, with Wainscoat claiming that this time Sandera went into a rage as she was ‘distraught due to the recent death of one of her cats.’
He claims she began screaming at him ‘Where are my kittens?’ and then began hitting him with a closed fist before throwing ‘a full bottle of Gatorade, which hit him in the back of the head.’
He says he did not file charges on account of her ‘drinking.’
The marriage finally blew up in June 2003, when police responded to another domestic disturbance with Wainscoat claiming he was ‘being battered by his wife.’
In court papers Sandera said she was not an alcoholic but had quit booze and attended AA meetings.
In addition, Sandera said she attended ’15 anger management classes.’
Eastwood is father to eight children by six different women.
Morgan Eastwood, 27 – whose wedding Clint recently attended – is his only child with Dina.
‘The former couple married in March 1996 and Morgan was born that December.
They separated in 2012 and Dina filed for divorce the following year citing ‘irreconcilable differences.’
Before Dina, Clint had an ‘open marriage’ with Maggie Johnson that lasted from 1953 to 1984. During their union, they welcomed daughter Alison, 52, and son Kyle, 56.
His eldest child, 70-year-old daughter Laurie Murray, was the result of a 1953 fling. Without Clint’s knowledge, Laurie’s mother — whose identity has never been revealed — got pregnant and put the baby up for adoption.
Laurie was adopted by a couple in Seattle and later learned Clint was her father after embarking on a quest to locate her birth parents.
A family friend told DailyMail.com back in 2018: ‘This all happened around 30 years ago. Laurie had been really interested in finding out who her real parents were and hired someone to help her. When they found the paperwork, her biological mother had written down Clint Eastwood’s name.
‘From what it appeared, Clint Eastwood had no idea that she was even pregnant.’
The news was received positively by Clint and his family. He took Laurie to the Oscars in 2004 and they’ve bonded over golf as adults.
Clint’s second eldest Kimber Lynn, 59 — who works as a pro makeup artist in Hollywood — was born in 1964 during Clint’s affair with dance/actress Roxanne Tunis, who passed away last year at age 93.
Clint shares son Scott and daughter Kathryn, 36, with flight attendant Jacelyn Reeves, who he dated from 1985 to 1990.
His second youngest child, daughter Francesca Eastwood, was born during his relationship with Titanic star Frances Fisher, 72, in the early 1990s.
After his split from Dina in 2012, Clint moved on with actress/model Christina Sandera, 60, in 2014. The couple are still together and live in California.
Clint became a grandfather for the first time — to his initial knowledge — in 1984 with the birth of daughter Kimber’s son Clinton, 40.
But Clint’s eldest grandchild is actually Laurie’s 41-year-old son Lowell Thomas Murray IV, who works as a fitness trainer and is a former contestant on the 18th season of ABC’s The Bachelorette.
Laurie also shares a daughter named Kelsey, whose age is unknown, with husband Lowell Thomas Murray III.
Clint’s granddaughter Graylen, 30, was born in 1994 and is his son Kyle’s only child.
Finally, Clint’s youngest grandchild is six-year-old Titan. Titan belongs to Clint’s daughter Francesca and Greystone Park actor Alexander Wraith.