The beauty queen was “de-crowned” and stripped of her title by Miss Great Britain, after scenes showing the 20-year-old having sex were broadcast on Wednesday.
Holland was told about the development off camera and chose to remain in the house at the time.
ITV said in a statement: “Owing to an illness in the family, Zara Holland has left the Love Island villa to return to the UK. Our thoughts are with her and her family and we send all of our best wishes.”
Holland said of her departure: “I’m so sad to leave the villa but it’s important for me to get home and spend time with my mum while she gets better. I’ve had the time of my life on Love Island and would like to thank all of my fellow Islanders and the production team for all their support.”
ITV further added that she would be able to return to the show at a later stage if she wanted to and “depending on circumstances in the villa”.
The model, from North Ferriby in Yorkshire, expressed regret over getting intimate with 24-year-old scaffolder Alex Bowen.
Bowen is the former boyfriend of Loose Women star Vicky Pattison, the winner of I’m A Celebrity in 2015.
Following the incident, she said: “You know when you’re in the moment and it just happens. That’s really not like me at all. Why couldn’t we have just gone to sleep?”
Explaining their decision to remove her title, the Miss Great Britain organisation said the move was taken with “deep regret”.
The statement added: “We pride ourselves on promoting the positivity of pageants in modern society and this includes the promotion of a strong, positive female role model in our winners.
“The feedback we have received from pageant insiders and members of the general public is such that we cannot promote Zara as a positive role model moving forward.
“We wholly understand that everyone makes mistakes, but Zara, as an ambassador for Miss Great Britain, simply did not uphold the responsibility expected of the title.”
The organisation later tweeted a message to further explain its position.
“To be clear, we have no problem at all with sex - it is perfectly natural,” they said.
“We simply can’t condone what happened on national TV.”
Holland will be replaced for the remainder of the year by runner-up Deone Robertson, who had been crowned Miss North Lanarkshire.
Love Island presenter Caroline Flack criticised the decision to strip Holland of her title.
She tweeted: “Feel even more sorry for Zara now she’s been de-crowned. She’s a very sweet girl. What even is ‘Miss GB’? Are we living in the dark ages?”
Fans have started a petition calling for her to be given back the title. The petition has just over 3,000 signatures and has been shared on social media by celebrities and fans, including former Blue Peter presenter Anthea Turner.