Poynter dated Frankie Sandford of The Saturdays, until the pair briefly split up in March 2010. They reunited in April 2010, but split up again in November of the same year. Poynter has stated that they will not be getting back together for the third time. Poynter spent some time in rehab due to depression, alcohol and substance abuse. In February 2014, it was confirmed that he is in a relationship with Ellie Goulding.
Poynter is the bassist of pop rock band McFly (and supergroup McBusted), also providing backing, and on occasion, lead vocals. The youngest member of the band, Poynter joined when he was 15. He was also the last to join, when Danny Jones and Tom Fletcher, who already had been signed to a record deal with Island Records, held auditions for a bassist and drummer, the latter of which was secured by Harry Judd.
Poynter has co-writer credits on many of McFly's tracks, including the lead writer credit on their 2007 number-one single "Transylvania". Poynter has called "Transylvania" his favourite song that he has written. Poynter also wrote an unrecorded track called "Silence Is a Scary Sound", which features as a live recording on their third studio album Motion in the Ocean.
Before joining McFly, Poynter was in a band named Ataiz. In 2010, along with three other people, including Motion in the Ocean and Radio:Active producer Jason Perry, Poynter started a clothing line called Zukie, named after his pet lizard. Poynter owns 30 per cent of the business. In early 2011, it was confirmed that Poynter had started his own clothing range, by the name of 'Saint Kidd', a pirate-based company inspired by William Kidd.
Poynter and Fletcher have published two books, the first one being The Dinosaur That Pooped Christmas, about a boy who gets a pet dinosaur for Christmas, was released in October 2012. The sequel, The Dinosaur That Pooped a Planet, was released on 29 August 2013.