A standard $1\%$ w/v solution of CM-chitosan made from squid pen was added to milk at levels of $0.5sim3\%$ (v/v) to improve the yield and rheological properties of cottage cheese by whey protein retention. Cheese curd did not form at levels higher than $3\%$ (v/v) CM-chitosan standard solution. Yield and total protein of cottage cheese increased up to $2\%;by;11;to;42\%;and;17;to;38\%$ respectively, compared to control cheese. Whey protein losses were decreased by 11 to $42\%$ and thus accounted for all of the increase in yield. Anomalous results were obtained at the $0.8\%$ level, which neither improved yield or whey protein retention nor stabilized rheological parameters, and at the $0.5\%$ level, which improved yield and total protein without increasing whey protein retention. Elasticity and cohesiveness of CM-chitosan-containing cheese were generally improved and stabilized during storage. Monitoring of cheese chromaticity values for four weeks revealed a delay in the onset of yellowing in cheeses with CM-chitosan compared to the controls, while the concentration of added CM-chitosan had little influence on cheese chromaticity. The addition of CM-chitosan solution could be applied directly to industrial scale cottage cheese-making without the need for any modification of the production process.