AbstractIn this paper we introduce the concept of interval-valued Pythagorean fuzzy subsemihypergroup and interval-valued Pythagorean fuzzy weak bi-hyperideals in hypersemigroups. We show that the (˜α, β˜)−level set of interval-valued Pythagorean fuzzy weak bi-hyperideal is a weak bi-hyperideal in hypersemigroup. We characterize cartesian product of interval-valued Pythagorean fuzzy set and examine that the cartesian product of interval-valued Pythagorean fuzzy weak bi-hyperideals is also an interval-valued Pythagorean weak bi-hyperideal in hypersemigroups.