Though reactive extrusion is a well-established technology in polymer industry to synthesize or modify polymers, it is rarely used to flame retard polymers. This due to the fact that the reactive extrusion process is complex and lack of availability of suitable reactive flame retardant components. Flame retardation of polymer via reactive extrusion process can be considered sustainable approach as it avoids the use of organic solvents and reduces processing steps. In this presentation, our approach to flame retard polyamide 6 (PA6) via novel reactive extrusion process will be discussed. Divinyl phosphine oxide and piperazine as suitable reactive monomers was reacted via in situ Michael addition reaction to form physical networks of phosphine oxide macromolecules inside PA6 during the extrusion process. The extruded PA6 was chemically characterized, analyzed for rheological, thermal and fire properties. The modified PA6 was further converted into textile fibers and analyzed for leaching behavior and mechanical performance. In addition to earlier stated advantages, via such approach migration and leaching out of the flame retardants in thin film and fiber applications can be avoided.