"She was a truly kind and delicate Irish flower, too sensitive for this soil, to whom loving and being loved was all that sparkled," Carrey said in a statement, calling White "my sweet Cathriona."
"We have all been hit with a lightning bolt," he added.
Winter said a drug overdose was suspected because several pills were found near her body. The death was called into authorities as a suicide but a final determination has yet to be made, Winter said.
Celebrity website TMZ.com said White and Carrey, 53, met in 2012, had an on-and-off romance, and rekindled their relationship in May before splitting up last week.
Carrey, the slapstick star of comedy movies including "Dumb and Dumber," and "Bruce Almighty," ended a five-year relationship with actress Jenny McCarthy in 2010. He has two previous marriages that ended in divorce.
(Reporting by Jill Serjeant and Piya Sinha-Roy; Editing by Bill Trott and Richard Chang)