The Official Online RBS 6 Nations Store is open. The store has everything you need to get behind your team during the RBS 6 Nations, plus the store is now fully stocked with a much wider range of rugby merchandise.
But the 28-year-old was unstoppable at the Stadio Comunale di Monigo, clinically putting the Italian side to the sword.
Walker opened his account in the tenth minute before lock Ian Gough extended the lead.
Centre Ashley Back grabbed the third try before Walker completed his trio after the interval.
The result leaves Ospreys in third position in the Magners League while Treviso are seventh.