Ceon Broughton, from Enfield, north London, has been charged with manslaughter, Dorset Police said on Friday.
Michie, who was Holby City star John Michie’s daughter, was found dead at Bestival at Lulworth Castle in September last year.
An initial post-mortem examination showed no clear signs of assault on the 25-year-old’s body. Further examinations, including toxicology tests, have been carried out.
Detectives said that Broughton was known to Michie.
He was previously arrested on suspicion of murder and released under investigation.
On Thursday, he was re-arrested at an address in Enfield. He was charged on Friday.
He is due to appear before Poole Magistrates’ Court on Saturday.
Senior investigating officer Neil Devoto, of Dorset Police’s Major Crime Investigation Team, said: “Following a detailed investigation, we have consulted with the Crown Prosecution Service, which has this evening authorised a charge of manslaughter.
“It is important to stress – as is typical in such circumstances – that it would be entirely inappropriate for Dorset Police to comment further ahead of the trial.
“It is also important that nothing is published online or on social media that could affect a future criminal case. It is vital that the justice system is allowed to follow its course.
“Louella’s family has been updated with this development and our thoughts remain with them at this very difficult time.”
John Montague, Senior District Crown Prosecutor for the Crown Prosecution Service in Wessex, said: “Following a careful review of the evidence provided to me by Dorset Police I have today authorised the charge of Ceon Broughton with an offence of manslaughter by gross negligence, following the death of Louella Fletcher-Mitchie on 11 September 2017 at Bestival, which was held in Dorset.
“The Crown Prosecution Service reminds all concerned that criminal proceedings against Mr Broughton are now active and that he has a right to a fair trial. It is extremely important that there should be no reporting, commentary or sharing of information online which could in any way prejudice these proceedings.”
The victim’s father, who also starred in Coronation Street, said at the time of her death the family had lost their “angel”, describing her loss as a “tragic mistake, a tragic accident.”