The French international joined Rovers on an initial loan deal from Championship rivals Bradford Bulls last month.
Chisholm has scored 58 points for Featherstone in just four appearances and has now set his sights on a place in the top five.
"I'm delighted to join up, I've enjoyed my time here so far and hopefully we can make a real push for the top five, which is our aim," he said.
Meanwhile, Rovers CEO Davide Longo insists it was a "no-brainer" to make Chisholm a permanent member of the Rovers squad.
He added: "Making Dane one of our own players was really a no-brainer for us.
"He has been pivotal in a lot of good things we have done over the last few weeks. Thanks to FevLine lottery we have been able to complete this signing.
"We are still looking to strengthen the squad as we look towards the top five, and a real push on the FevLine lottery can help us do this.
"So it is a massive thank you to all of you who pay into this scheme who have helped us secure the signing of such a talented player."
Head coach Ryan Carr has watched Chisholm guide Rovers to three wins in their last four outings.
The half-back scored in Sunday's win over Rochdale Hornets and will now be available for the clash with Bradford Bulls at the end of May.
Carr added: "Dane has brought a lot to the team in the short time he's spent with us, he has integrated well with all of the boys, and we are delighted to secure his services."