The invention relates to a method for manufacturing a composite product comprising organic natural fiber material and matrix material, wherein the method comprises mixing the organic natural fiber material with the matrix material in a primary mixing stage to form a mixture. The primary mixing stage comprises a contacting step in which the organic natural fiber material comes in contact with the matrix material that is at least partly in a form of melt, and compression ratio of the organic natural fiber material is less than 8. The method further comprises forming a composite product comprising the mixture. Further, the invention relates to a composite product, a use of the composite product, and a system for manufacturing a composite product.