Ryan started at The Sun in 2009 as a general news reporter, and has been reporting at Westminster since 2015, initially on The Sun before moving to join the Sunday title, says the publisher.
Ryan Sabey said: "I'm absolutely delighted to be joining a great lobby team covering every political twist and turn in Parliament across print and online.
"Our reporting from Westminster is more crucial than ever keeping our loyal readers informed of the major issues such as the cost of living crisis."
Political editor Harry Cole said: "Ryan is a top scoop getter and can't wait for him to get breaking stories all week.
"His keen eye for the big picture and coming trends like the collapse of the Red Wall - which he was predicting long before other journalists - will be invaluable to our readers across print and online."
Sabey steps into the role of deputy political editor following the announcement that current deputy political editor, Kate Ferguson is to take up the role of political editor on The Sun on Sunday.
Both will start their new roles this summer.