She stars on and is best known from the Music Television series Before, Holly worked for Her Majesty Revenue and Customs and in sales at a Santander call centre, in hopes of launching a career as a glamour model. After applying for, and securing a place on the show she eventually quit her job. Holly has featured in many men"s magazines including Nuts with a photoshoot with fellow cast mate Vicky Pattison as well as by herself on several occasions.
She has also appeared on the cover of both the United Kingdom"s FHM and Loaded.
In July 2012 she posed naked for a photoshoot with the magazine. This was her first naked photoshoot.
In August 2012 Hagan appeared nude in a photoshoots for Oklahoma! and Heat showcasing her 3 stone weight loss. Holly Hagan began her public career on Music Television series in 2011 at the age of 18.
Her opening statement on the show was "I"m fit, I"m flirty and I"ve got double F"s".
She has starred in all eleven series of the show, featuring in every episode except episode four of the first season. In the seventh series, her most notable "clash" was with newcomer Marnie Simpson and the two got into an altercation. In an interview with United Kingdom Now Magazine, Holly said the two of them "don"t speak".
However, they are now friends.
Also in the seventh season, Holly celebrated her 21st birthday. Holly enters the house in season 10 with Kyle.
In October they made their relationship official and were boyfriend and girlfriend, before a dramatic break-up in Series 11 of the show, shown between October and December 2015.