His closest rival is Billy Slater with 39,439 running metres. Gallen made 21 appearances for Cronulla in 2018 as the club reached the preliminary final before losing to Melbourne 22-6. Gallen did not feature in the match as he suffered an injury the previous week in Cronulla's victory over Penrith. In October, Gallen signed a one year contract extension to stay at Cronulla for the 2019 season. The deal will make him the first man to play 19 consecutive seasons with an NRL club. In November, Gallen spoke to the media in the aftermath of Valentine Holmes leaving the NRL in hopes of gaining an NFL contract. Gallen said “He's won a premiership with us, he's been our best player. But the way this has happened, I'm disappointed, Not only does he have a Sharks contract, he has an NRL contract. Now the NRL are always on about the integrity of the game, I don't see how this is good for the integrity of the game. A bloke breaking a contract with one year to go and just walking out on a club and the game. I think it's got to be a minimum two-years out of the game, if not out forever". Gallen's comments faced a negative reaction by former players such as Chris Walker and Mat Rogers. Rogers spoke to the media saying “I think Gal's overreacted,” Rogers told AAP. “For someone who goes and cops money for fighting while he's contracted, it's unbelievable that he'd come out and say something so stupid. Oh mate, Gal, keep your mouth shut mate". Walker attacked Gallen on social media claiming Gallen was pushing negativity into the NRL. Gallen responded to Walker's tweet saying "Yesterday's news from yesterday's hero, clubs moved on Chris you should try. The game hasn't left the papers since GF cause of issues like this & coaches they say any publicity is good publicity maybe that's why you keep involving yourself in something that doesn't concern you. Jog on". On 10 March Gallen rebuked Melbourne Player Cameron Smith and his calls for Melbourne's 2007 and 2009 premierships to be reinstated after Smith accused the NRL over double standards in relation to Cronulla's salary cap breaches. Smith was upset that Melbourne had been stripped of the 2007 and 2009 premierships yet Cronulla were allowed to keep their premiership. Gallen responded by saying "We went in and self reported a $50,000 discrepancy, which the CEO thought was all it was.