Head coach Clive Griffiths previously worked with both players while coach of the Wales Students side and Great Britain Students assistant coach.
Crusaders have also named former Great Britain and St Helens prop John Fieldhouse as Griffiths’ assistant.
Prop Owain, 27, and 25-year-old second row forward Iwan first played rugby league with Wrexham Raiders.
Owain said: “Both myself and my brother are delighted to be able to represent our home town club and can’t wait to get into training.
“We’ve always been massive rugby league fans and when the call came from Clive Griffiths we both jumped at the chance.
“It will be brilliant to be able to play at the Racecourse, which is a fantastic ground in front of our friends and families.”
Griffiths said “These two boys have a huge amount of experience and will be a massive asset to the squad.
“The fact that they are local lads just makes it all the more special.”
Both Owain and Iwan were part of the successful Great Britain Students squad which toured Bali and Australia earlier this year.
Meanwhile, Griffiths believes the addition of Fieldhouse as his assistant will prove to be a shrewd appointment.
The pair have previously worked together at South Wales RLFC in 1996 and on the backroom staff at Warrington Wolve
“I wanted someone who I could trust as my assistant and I have known John for years,” he said.
“He is an experienced campaigner with a wealth of knowledge and experience and has done a really good job with the BARLA Great Britain side and has brought a lot of amateur players through that have gone into the professional ranks.
“He knows the territory around here as well and historically ticks all the boxes for me. I’m delighted to have him on board.”
Griffiths hopes to announce further signings later this week.