The Hollywood filmmaker, 78, and his wife, Michele Singer Reiner, 68, were found dead inside their Brentwood home on Sunday (December 14).
Police and firefighters were called at 3.38pm local time for medical aid to a property in the LA neighborhood.
Authorities later confirmed the couple had died from stab wounds.
The incident is being investigated as an apparent homicide.
Police said on Sunday that no one had been arrested and no suspect or person of interest was currently being sought.
No further details have been released.
Tracy Reiner has spoken out (Bobby Bank/WireImage/Getty Images)
Tracy Reiner has spoken out (Bobby Bank/WireImage/Getty Images)
Rob was the father of four children; he adopted his eldest, Tracy, during his marriage to actress and director Penny Marshall between 1971 and 1981. She is the daughter of Marshall and her previous husband Michael Henry.
Tracy has since told NBC News entertainment correspondent Chloe Melas she is 'in shock' over the devastating news.
She said: "I came from the greatest family ever. I don’t know what to say. I’m in shock."
Tracy, who is married and has five children of her own, is an actress and featured in movies including A League of Their Own, Die Hard, and Apollo 13.
She also played girlfriend Emily in Rob's When Harry Met Sally rom-com.
Rob and Michele Reiner married in 1989 (Eric Charbonneau/Getty Images for Netflix)
Rob and Michele Reiner married in 1989 (Eric Charbonneau/Getty Images for Netflix)
The iconic movie is also how Rob met future wife, photographer Michele.
In fact, their paths crossing changed the ending of the entire film.
Rob and Michele married in 1989 and went on to have three children together: sons Jake and Nick and another daughter, Romy.
The pair went on to direct and produce movies together, including Shock and Awe and Spinal Tap II: The End Continues, which released earlier this year.
A family spokesperson told the media: "It is with profound sorrow that we announce the tragic passing of Michele and Rob Reiner.
"We are heartbroken by this sudden loss, and we ask for privacy during this unbelievably difficult time."
Spinal Tap star Chris Guest and wife Jamie Lee Curtis have paid tribute (Alberto E. Rodriguez/FilmMagic)
Spinal Tap star Chris Guest and wife Jamie Lee Curtis have paid tribute (Alberto E. Rodriguez/FilmMagic)
Elsewhere, tributes have flooded in for the couple.
California Governor Gavin Newsom also said he was 'heartbroken' by the news and called Rob a 'big-hearted genius behind so many of the classic stories we love.'
Spinal Tap and The Princess Brides star Christopher Guest and his wife, esteemed actress Jamie Lee Curtis, said they were 'numb, sad and shocked' about 'the violent, tragic deaths' our dear friends Rob and Michele'.
In a statement, they continued: "...our ONLY focus and care right now is for their children and immediate families and we will offer all support possible to help them."
They added: “There will be plenty of time later to discuss the creative lives we shared and the great political and social impact they both had on the entertainment industry, early childhood development, the fight for gay marriage and their global care for a world in crisis.
“We have lost great friends. Please give us time to grieve," they concluded.