Meldrum's acid-based condensations were employed as a new method to develop two- and three-component postpolymerization modifications of polymers with conversion up to more than 99% at room temperature. Acrylic polymers containing Meldrum's acid could be functionalized with a diverse scope of aldehydes yielding Knoevenagel condensates and functionalized with both aldehydes and nitromethane, leading to a library of polymers containing gamma-nitrocarbonyl groups. Additionally, a novel thermal and aggregation-induced emission dual active polymer was constructed via two-component postpolymerization modification of a copolymer featuring thermal-responsive and Meldrum's acid units.