In March 2014, Mc Donnell announced on his blog that he has terminated his friendship and cohabitation with Alex Day, stating that "I just don’t feel able to call Alex a friend of mine anymore", following allegations that Alex sexually manipulated, emotionally abused, and cheated on past girlfriends.
After setting up the You Tube channel, "charlieissocoollike" in April 2007, Mc Donnell started posting video blogs (or "vlogs") to a small audience.
He first came to prominence when his video titled "How To Get Featured on You Tube" became popular after it was featured on You Tube's UK homepage.
In January 2008, in celebration of gaining 25,000 subscribers, Mc Donnell asked for challenge suggestions from subscribers, and he is completing them in a series of 25 videos titled "Challenge Charlie".
He has completed all of these challenges as of March 2013, one of which was suggested by TV presenter, Phillip Schofield, and his daughter Molly, challenging Mc Donnell to perform the dance that accompanies the song, "Hoedown Throwdown", made popular in the film Hannah Montana: The Movie.
Mc Donnell has since posted a wide range of videos on the site including his most viewed "My American Accent".
In 2008, Mc Donnell participated in a video-blog collaboration with four other You Tube personalities, titled "Five Awesome Guys," a spin-off project of the "Five Awesome Girls" which featured hayleyghoover and italktosnakes and ran from 28 January to 31 December of that year.
On 15 June 2011, his You Tube channel charlieissocoollike became the first in the UK to reach one million subscribers, and in May 2013, his channel reached two million subscribers.
As a musician, Mc Donnell was a member of Doctor Who-themed rock band Chameleon Circuit and was also a member of the short-lived project Sons of Admirals until it was disbanded in May 2011.
In 2010, Mc Donnell released his debut solo album, titled This Is Me.
Mc Donnell began directing short films in May 2013, and currently co-hosts the weekday morning You Tube breakfast show Cereal Time with fellow You Tube vlogger Jimmy Hill.
Mc Donnell was born and raised in Bath, Somerset to parents Lindsey and Mark.
He has two siblings: his younger brother, William, and his younger sister, Bridie.
He was educated at Beechen Cliff School, Mc Donnell used to live with fellow video blogger Alex Day, but currently resides in his own apartment in London with his girlfriend.