Nathan James Sim, aged 32 has been missing since Saturday evening.
The young father was last seen at around 7pm on Quai Saint-Croix in the centre of Bordeaux.
His family told The Local he had been visiting Bordeaux for the day and had been working in Lormont, a suburb of Bordeaux, decorating a holiday cottage.
They have not been able to contact him via his mobile phone since he went missing.
His partner Sally Louise launched an appeal on Facebook: “I am posting this in the hope that a friend of a friend of a friend might share it and it might reach someone who knows his whereabouts. Please, please share and get this photo as widespread as possible.”