A heartwarming video has emerged of singer JJ Hamblett surprising his son Princeton J Alexander in hospital after they hadn't seen each other for eight months.

The footage, shot last in Phoenix, AZ, USA, shows Hamblett entering the hospital room dressed as the three-year-old's favourite Power Ranger, the Black Ranger.

Hamblett eventually removes his costume and his son runs into his arms.

"Princeton immediately ran to his dad who he hadn't seen for eight months as JJ Hamblett is based in London and just finished up a tour with his boy band Union J," his mother, Caterina Lopez, wrote online.

"Only the video can truly capture his adorable reaction when he realizes it's actually his father under the costume," she added.