Cephalopods, a diverse class of carnivorous marine predators, exhibit a wide range of feeding behaviours and foraging strategies related to their lifestyle, habitat and morphological adaptations. Their beaks play a crucial role in capturing and processing prey. This study investigates the link between the shape of the rostrum of cephalopod beaks and their function through a mix of experimental and computational approaches. Fourteen upper beak rostrum models from a range of cephalopod species, representing their morphological and ecological diversity, were 3D-printed, and subjected to uniaxial puncture tests. Force and displacement were recorded to estimate puncture ability. Finite Element Analysis (FEA) was used to explore the form–function relationship under loading conditions mimicking biting and pulling, analysing stress patterns across different rostrum morphologies. The results show that rostrum size significantly influenced puncture performance, with smaller rostra requiring less force and displacement for puncturing. However, larger rostra exhibited higher structural stiffness, suggesting increased vulnerability to stress during biting. Morphology-driven tests demonstrated species-specific differences in puncture abilities, with rostrum sharpness playing a crucial role. FEA results further indicated that longer and sharper rostra were more susceptible to stress, potentially impacting their overall structural integrity. The findings highlight the trade-off between rostrum size and sharpness in cephalopod beaks, with implications for prey selection and feeding efficiency. The study contributes to understanding the morpho-functional aspects of cephalopod beaks and their role in prey capture and consumption, shedding light on the evolutionary pressures shaping these remarkable marine predators.