It is an object of the present invention to provide a cellulose-containing composition having excellent coating suitability, a production method thereof, and a film. According to the present invention, provided is a cellulose-containing composition comprising cellulose fibers having a fiber width of 1000 nm or less and protein, wherein the protein includes an enzyme, the content of the protein is 1×10−3 parts by mass or less with respect to 1 part by mass of the cellulose fibers, and when the cellulose-containing composition having a solid concentration of 0.4% by mass is obtained, the viscosity of the cellulose-containing composition measured under conditions of 25° C. and a rotation number of 3 rpm is 10 mPa·s or more and 11000 mPa·s or less.