Removal of noxious dyes and oils from the modern day industrial discharges is compulsory to safeguard humans, aquatic organisms and water quality and to prevent ecological damages induced by pollutants. The underscored problems were addressed by one pot fabrication of sodium alginate grafted poly (acrylic acid-co-N-vinyl formamide) [SA-g-p(AAc-co-VFA)] hydrogel. The hydrogel swelled in water up to 7665% due to water absorption through Fickian diffusion. The smart hydrogel efficiently performed sorption of methylene green (MG) from aqueous solution owing to outstanding swelling potential and electrostatic interactions. The maximum sorption potency of the adsorbent reached to 1915 mg g−1 with excellent removal at 5 and ˃ 11 pH values. The MG-sorption followed pseudo second order kinetic and Langmuir isotherm models, thus indicating chemisorption of cationic-MG onto anionic sorbent due to the development of electrostatic bond. The used [SA-g-p(AAc-co-VFA)/MG] sorbent was tested for oil (toluene as oil probe) separation from its aqueous emulsion. The material exhibited 94% separation efficiency toward toluene eradication which remained unchanged for five successive runs. The remarkable swelling and sorption potencies of the hydrogel coupled with the outstanding toluene separation efficiency of the MG-sorbed hydrogel make the subject hydrogel a versatile material for relevant industrial and environmental applications.