The actress went to the Caribbean at the end of February, having received treatment for exhaustion following her dramatic collapse of the previous month. A source said she was on holiday at a secret location to have a "reality break".
Now the 49-year-old mother of Scout, Tallulah and Rumer Willis is back in Los Angeles, according to TMZ.
After photographs of Moore stepping off a private plane in California with good friend Eric Buterbaugh were posted on Sunday, the star - who separated from husband Ashton Kutcher last year - is thought to be well on her way to recovery.
Moore was spotted going through customs in Ft. Lauderdale, Florida before continuing on to California, according to a source.
She had previously entered treatment after being rushed to a hospital in January. She was said to have "smoked something" before she collapsed.
> Rumer Willis's Hollywood home broken into, $10k worth of goods stolen
> Demi Moore visited by Ashton Kutcher after rehab stint