The agricultural industry generates considerable amounts of agro-food waste that cause environmental and socioeconomic challenges. In line with the 2030 Agenda, one proposed strategy is to integrate agricultural waste to a second process through the recovery of high-value compounds using green technologies. In this context, Carya illinoinensis shells are an agricultural by-product waste where annual production in Mexico reaches approximately 171,000 tons, with shells representing 40–50% of total weight fruit (around 68,400 tons of residue). This residue has attracted attention due to their composition rich in bioactive phytochemicals, particularly polyphenolic compounds such as phenolic acids and flavonoids. These compounds are considered eco-friendly and renewable alternative for pest management. Unlike synthetic pesticides, which are associated with environmental human health risks and the development of resistant pest. This review summarizes current knowledge on the efficacy of phytochemicals extracted from pecan nutshells and the in vitro and in vivo activities reported against crop pests, including insects, microorganisms and weeds, while emphasizing the potential of green technologies to reduce agricultural waste reusing them and simultaneously decrease the use of synthetic products for pest control.