Catalytic methods that introduce functional groups via carbon–carbon bond cleavage steps have typically been limited to moieties activated by strain or by directing groups, with few transformations engaging the bonds of only sp3-hybridized carbon atoms in saturated hydrocarbons. Here, we report the conversion of catenated carbon chains in polyolefins, which currently represent >50% of discarded plastics, into shorter aliphatic alkylaluminum species via a sequence of zirconation via C–H bond activation, β-alkyl elimination for carbon–carbon bond cleavage, and heterobimetallic alkyl group exchange for carbon–aluminum bond formation. The versatility of aliphatic alkylaluminum species is exemplified by their subsequent conversion into high-value fatty acids or alcohols, which have applications as biodegradable surfactants and detergents. A technoeconomic analysis indicates that fatty alcohols produced from discarded polyolefins are cost competitive with conventional syntheses. Thus, this process could ameliorate economic and environmental challenges of the plastic-waste crisis.