Club bosses say Williams will stay with the Sea Eages for “several” more seasons, while 26-year-old Robertson looks likely to finish his career at Brookvale after agreeing a substantial deal.
Robertson, who scored a hat-trick in their 2008 grand final triumph over Melbourne, has scored 46 tries in 104 games for the club.
Williams, meanwhile, has so far weighed in with an impressive 38 tries to his name while at Brookvale.
Coach Des Hasler will be looking to improve on last season’s performance which saw them finish a credible fifth in the NRL table, but fall to an embarrassing 40-12 defeat against Melbourne in the qualifying finals.
Hasler says that the re signing of the club’s wing specialists was vital for the immediate future of the club.
He said: “They have developed well at Manly after initially joining the club for an opportunity. They are both proven in big matches and are excellent finishers”.
Robertson said he was delighted to extend his career with the club.
He said: “My time here has been my best in football so I never wanted to go anywhere. I’m happy to play out my career in the NRL with the club. Like everyone else here I want to get stuck into a good off season to again play finals football in 2010”.
He added: “I was up and down last season – I want to be consistent in the upcoming season”.