Several American tabloid newspapers have in recent weeks published lurid details of their secret relationship which were revealed shortly after Mr Bezos, the world's richest man, went public about his divorce in a statement on Twitter on Jan 9.
Who is Ms Sanchez? Here are five things about Mr Bezos' rumoured new romance.
1. She is a long-time television personality
Ms Sanchez's first foray into journalism was during an internship with Los Angeles television station Channel 13. She was then studying at the University of Southern California on a scholarship, said The Hollywood Reporter.
She later made a name for herself on television channel Fox's Good Day LA, which she co-hosted from 2011 to 2017.
According to entertainment news site People.com, she was the original host of dancing competition series So You Think You Can Dance, but left the show after the first season to have her second child.
She also starred in small roles for movies including The Longest Yard, The Day After Tomorrow, Fight Club and Ted 2.
Born in Albuquerque, Ms Sanchez is a third-generation Mexican-American.
2. She wed a Hollywood talent mogul, but will soon part ways
Ms Sanchez tied the knot with Mr Patrick Whitesell, who is known as one of Hollywood's most powerful men, in a star-studded celebration in August 2005.
He is the co-chief executive officer of Hollywood talent agency WME, and the couple's wedding was said to have cost at least US$2 million.
Mr Whitesell is the agent for notable stars such as Matt Damon and Ben Affleck, who both reportedly attended the couple's lavish wedding. Other celebrity guests included Jennifer Garner, Jessica Alba and Hugh Jackman.
However, news reports said that Ms Sanchez and Mr Whitesell had separated in the second half of last year after 13 years of marriage.
3. She has dated several high-profile men
United States entertainment website Radar Online reported that Ms Sanchez once dated former National Football League star Tony Gonzalez in 2001. The pair have a 17-year-old son named Nikko.
She was also once engaged to NYPD Blue actor Henry Simmons, but they broke up in 2003.
She has two children with Mr Whitesell: Evan 12, and 10-year-old Ella.
4. She is a licensed pilot, who now flies helicopters for movies
"I had my job, I had a career, and then I found a calling," Ms Sanchez told The Hollywood reporter in a 2017 interview, where she spoke at length about her love for flying.
Ms Sanchez earned her helicopter licence in June 2016, while she was still working as a news anchor.
She told The Hollywood Reporter that she started flying planes in 2011, but later on, decided to take her passion more seriously by enrolling in flying school.
However, she faced several challenges, partly because she has dyslexia.
"I literally had to put myself in a room and just cram to figure it out," she was quoted as saying.
After getting her licence, Ms Sanchez founded her own aerial film and production company Black Ops Aviation in 2016.
Some movies she has consulted on for aerial sequences include Christopher Nolan's Dunkirk (2017).
Ms Sanchez also told The Hollywood Reporter that she hopes more women could experience flying.
"This space is dominated by men. But there's nothing physical about flying a helicopter. You can be 5-foot-1 or 6-foot-4. There's no reason more women aren't in this," she said.
5. She first met Bezos several years ago
Ms Sanchez reportedly met Mr Bezos and his wife in Seattle some years ago and was impressed by him.
British tabloid website Daily Mail said that she had told a close friend of hers: "Now that's the kind of guy I need."
In 2016, Mr Bezos was photographed together with Ms Sanchez and Mr Whitehall at a party for drama film Manchester By The Sea. The film was produced by Matt Damon and distributed by Amazon.
American tabloid magazine The National Enquirer, which obtained text messages allegedly revealing intimate details of their relationship, claimed that they had began their affair about eight months ago.
Mr Bezos and Ms Sanchez have yet to make their first official public appearance together, though there has been widespread speculation that they have met secretly several times in recent weeks.