A process for manufacturing knitwear, hosiery or seamless textile items with variable compression on circular weft knitting machines, comprising the steps of: - providing at least one circular weft knitting machine comprising at least: a bearing structure ; a cylinder of the needles rotatably mounted in the bearing structure ; a plurality of needles supported by the cylinder and movable parallel to an axis of rotation of the cylinder to produce a knitted fabric; a plurality of stitch adjusting cams operatively active upon said needles and selectively movable to vary the width of the stitches produced by the needles; at least a first feeding device of an elastic yarn operatively active to supply the needles with the elastic yarn at a respective feeding position ; a control device of the operation of the knitting machine ; and electric and electronic devices connected to the control device and operatively active to control the operation of a plurality of parts of the knitting machine and to detect a plurality of operating parameters of the knitting machine ; - activating a program for manufacturing a knitwear or hosiery or a seamless textile item , on the control device of the knitting machine ; and - manufacturing a knitwear, hosiery or seamless textile item on the knitting machine; the process being characterized in that it further comprises the step of actively and automatically changing, according to a predefined program for manufacturing the textile item, the feeding tension of the elastic yarn fed to the needles at least by the first feeding device according to a predefined value of variation and for a predefined number of times, corresponding to at least two times within the same knitting row during the production of the textile item , to define in said same knitting row of the textile item a corresponding predefined number of distinct knitting row portions having a mutually differentiated yarn tension corresponding to at least two portions of the same knitting row, wherein - the step of changing the feeding tension of the elastic yarn is performed independently from a variation in the position of the stitch adjusting cams ; and - the tension of the elastic yarn , the elasticity and the compression degree obtained in different areas of the textile are varied without changing the knitting structure produced. - providing at least one circular weft knitting machine comprising at least: a bearing structure ; a cylinder of the needles rotatably mounted in the bearing structure ; a plurality of needles supported by the cylinder and movable parallel to an axis of rotation of the cylinder to produce a knitted fabric; a plurality of stitch adjusting cams operatively active upon said needles and selectively movable to vary the width of the stitches produced by the needles; at least a first feeding device of an elastic yarn operatively active to supply the needles with the elastic yarn at a respective feeding position ; a control device of the operation of the knitting machine ; and electric and electronic devices connected to the control device and operatively active to control the operation of a plurality of parts of the knitting machine and to detect a plurality of operating parameters of the knitting machine ; - activating a program for manufacturing a knitwear or hosiery or a seamless textile item , on the control device of the knitting machine ; and - manufacturing a knitwear, hosiery or seamless textile item on the knitting machine; - the step of changing the feeding tension of the elastic yarn is performed independently from a variation in the position of the stitch adjusting cams ; and - the tension of the elastic yarn , the elasticity and the compression degree obtained in different areas of the textile are varied without changing the knitting structure produced. <EOS>