Gagan, 24, made his debut for the Cronulla-Sutherland Sharks in 2014 before moving on to the Newcastle Knights.

He has 8 NRL games under his belt for both the Sharks and Knights. 

Meanwhile Martin, 20, signs on from the Manly-Warringah Seal Eagles. 

Martin led the Manly U20 side as captain through their title-winning season in 2017.

“Jacob was the Rookie of the Year for the Sharks in 2014 and unfortunately has had an injury-interrupted few years,” Rabbitohs head coach Anthony Seibold said. 

“He really showed his potential at the end of the 2014 season and we’re giving him an opportunity to find that form again within our squad. 

“Jacob will add depth to our outside backs and he will create more competition for spots in our top 17 which is very important for any NRL squad. 

“We’re all looking forward to seeing what Jacob can achieve here at Souths.” 

“Jesse comes to us following a very successful year leading Manly’s under 20s team to a Grand Final win, and we’ll be helping him take the next step up to the NRL level over the 2018 pre-season. 

“He’s renowned for being a very hard worker, especially in all of the effort areas of the game, and we’re looking forward to seeing Jesse progress and develop with this opportunity. 

“He’ll be given every chance throughout our pre-season training to step up and we’re all looking forward to working with him.”