An aqueous biosurfactant solution, a biobased green acidic catalyst for Knoevenagel condensation of 1,3-indanedione with aryl aldehydes and tandem Knoevenagel–Michael reaction of 3-methyl-1-phenylpyrazole with aryl aldehydes, has been reported for the first time. The synthetic pathway complies with several key requirements of green chemistry principles such as the use of renewable feedstock, aqueous conditions, waste prevention, atom economy along with the biodegradable and recyclable catalyst. Thus the presented protocol offers an attractive option because of its versatility, ecological safety, environmental acceptance and sustainability.