Cost-effective production of proteases those are robust enough to function under harsh process conditions are always sought after due to their wide industrial application spectra. Solid-state production of enzymes using agro-industrial wastes as substrates is an environment-friendly approach, and offers several advantages like high productivity, cost-effectiveness, less labour intensive and lesser effluent production, among others. In the current study, different agrowastes were employed for thermoalkali-stable protease production from Bacillus subtilis K-1 (BSK-1) under solid state fermentation. Among several agricultural residues examined cotton seed cake supported maximum protease production (728 Uml−1), and was followed by gram husk (714 Uml−1), mustard cake (680 Uml−1), and soybean meal (653 Uml−1). Plackett-Burman design of experiment showed that peptone, moisture content, temperature, phosphates and inoculum size were the significant variables which influenced the protease production. Furthermore, statistical optimization of three variables viz. peptone, moisture content and incubation temperature by response surface methodology resulted in 40% enhanced protease production as compared to that under unoptimized conditions (from initial 728 Uml−1 to 1020 Uml−1). Thus, solid-state fermentation coupled with design of experiment tools represents a cost-effective strategy for production of industrial enzymes.