The title means that the Rams have won automatic promotion to the Championship.
The Cougars, second in Championship one, will have the chance to gain promotion via the play-offs in October.
Walker and Jones traded penalties in the final moments before half time, making the interval score 14-8 in Dewsbury’s favour.
The Rams sealed the win in a devastating 20-minute period from the 50- to the 70-minute mark in which seven tries were scored, all but one converted by the prolific Walker.
The Cougars gained some consolation with the final try just minutes from time, fittingly scored by Presley who was arguably Keighley’s best player, Jones converting.