A flame-retardant aconitic acid-derived cross-linker, a process for forming a flame-retardant resin, and an article of manufacture comprising a material that contains a flame-retardant aconitic acid-derived cross-linker are disclosed. The flame-retardant aconitic acid-derived cross-linker can have at least two phosphoryl or phosphonyl moieties with allyl functional groups, epoxy functional groups, propylene carbonate functional group, or functionalized thioether substituents. The process for forming the flame-retardant polymer can include forming an aconitic acid derivative, forming a phosphorus-based flame-retardant molecule, and reacting the aconitic acid derivative with the phosphorus-based flame-retardant molecule to form a flame-retardant aconitic acid-derived cross-linker, and binding the cross-linker to a polymer. The aconitic acid derivative can be synthesized from aconitic acid obtained from a bio-based source. Examples of aconitic acid derivatives include carboxysuccinic acid, 2-(hydroxymethyl)-1,4-butenediol, and 2-(hydroxymethyl)-1,4-butanediol. The article of manufacture can further comprise an electronic component.