A cable tie tensioner includes a first plate body and a second plate body. The first plate body includes a first pivot portion, a first operation handle, and a cutting member. The second plate body includes a second pivot portion and a second operation handle corresponding to the first pivot portion and the first operation handle. The second plate body is provided with a pressing member. When in use, a tie section of a cable tie is inserted through the pressing member, the second operation handle is operated to move toward the first operation handle, and the pressing member clamps the excessive tie section of the cable tie to be pulled so that an article can be tied up. After the article is tightened, the cutting member is used to cut off the excessive tie section of the cable tie.