Captain Danny McGuire was the star of the show on his farewell appearance for his hometown club, scoring two tries to lead the Rhinos to their second title in the last three years.
Castleford finished 10 points clear of the Rhinos in the regular campaign, but they failed to cap off their greatest ever season with a fitting performance in their first Grand Final appearance.
Instead, the Tigers were forced to settle for only the League Leaders' Shield as they were swept aside by the more experienced club on these stages.
McGuire also helped to create a brace of tries for Tom Briscoe in addition to landing two drop goals in his man-of-the-match display, bringing a dream end to his 16-year Leeds career.
Castleford were forced to wait until the 79th minute to get on the board at all as Alex Foster notched a late consolation, but it was a day to forget for the Tigers as they failed to turn up on the big stage.