The news will be a welcome boost to Robins fans who have seen the England star have an immediate impact this season on his arrival from NRL club Sydney Roosters.
Hall, 33, has scored 15 tries to leave KR in fifth spot and hoping to secure a play-offs spot in their final regular round game at Leeds Rhinos tomorrow.
He had initially signed a two-year deal but this now takes him to the end of 2023.
Hall, who scored 232 tries in 327 games for hometown Leeds Rhinos and is England's record try-scorer, will be approaching his 36th birthday by that point but Smith has no concerns.
He has been ever-present this term until suffering a shoulder injury last week which keeps him out for the remainder of the campaign.
Hall is in Super League's top ten performers for metres made (2590) and carries (310) while only Ken Sio has scored more tries.
Moreover, his partnership with captain Shaun Kenny-Dowall on KR’s left edge has been key to the Robins’ defence out wide.
“Ryan's been great in all aspects of having a good pro here from performance to try-scoring and leadership, he's been terrific," said Hall.
“He's very professional and has been a really good influence.
"He takes care of himself and he's in great shape. I know he's got an injury at the minute but that's part and parcel of Rugby League. It’s not an issue that's going to restrict him very long, he'll be ready for preseason.
"The way he's approached this year is just 100% and he gives that all the time. I think for somebody who takes good care of himself and trains so hard, Ryan's got potential to play on for a long time yet”.