A method for making nanofibrillar cellulose includes mixing anionized or cationized cellulose fibers and cellulose pulp to a mixture including at least 1% and below 90 wt-% cellulose pulp based on dry weight, and subjecting the mixture to a refiner stage where the anionized or cationized cellulose fibers are at least partly reduced to nanofibrillar cellulose and the cellulose pulp acts as auxiliary pulp, and obtaining a mixture of nanofibrillar cellulose and cellulose pulp from the refining stage. The mixture can be used for making paper by adding it to base pulp.