The singer-songwriter joined girlfriend Anais Gallagher at the star-studded event. Anais' mum Meg Mathews is patron of PupAid and one of the organisation's biggest supporters, while Anais has appeared in a campaign for the charity.
PupAid campaigns against the UK practice of puppy farming, and seeks a ban on puppies and kittens sold without their mothers present.
The PupAid Fun Dog Show in London on Saturday, 5 September included fun competitions for 'Waggiest Tail', 'Best Rescue' and 'Dog That Most Looks Like A Celebrity'.
Reece joined Anais, Meg and their Boston terrier Oscar at the event, while other celebrities who lent their support on the day included Rachel Riley, Jo O'Meara, Matt Cardle and former TOWIE star Kirk Norcross, who arrived with pregnant girlfriend Holli Willis.
Anais and Meg starred together in PupAid's 'Where's Mum? Campaign, which was designed to help the UK public choose a healthy, happy puppy.
For more info on PupAid please visit its official website here