Johnson is set to reunite in the halves with his former Warriors teammate next season, after he was granted a release from the Auckland-based club last week before signing a three-year contract with Cronulla.
Townsend is looking forward to again teaming up with the Kiwis test star after the pair combined during his two-year stint at the Warriors between 2014 and 2015.
"We're very excited to have him on board and in our team," Townsend told Radio Sport's D'Arcy Waldegrave.
"The biggest thing about Shaun is he's just a great bloke and someone I got on with really well while I had my time at the Warriors.
"We were able to hang out off the field and play a bit of golf, and around the sheds he's really easy going and a good bloke, and at the end of the day that's all you want.
"You want someone who's going to come in and put the team first and that's the type of player he is, so we're looking forward to having him here."
But while Johnson practically owned the No 7 jersey and Townsend predominantly started at No 6 at the Warriors, the duo are now set for a role reversal, with the Cronulla local junior having settled in at halfback since he returned to the Sharks in 2016.
After installing Matt Moylan at five-eighth this year, Townsend confirmed Cronulla coach Shane Flanagan is set to return the former Penrith captain to fullback to allow Johnson to play at No 6.
It won't be a big adjustment however, as Johnson has always tended to play more like a five-eighth regardless of the number on his back, and Townsend, like Warriors playmaker Blake Green this season, was generally the side's main organiser.
"Our coaching staff will have a bit of a plan there and we've already briefly spoken about it, but we haven't gone into too much detail about numbers and things like that," he said.
"But at this stage I think Matt will shift to fullback which he's very familiar with so it's exciting times for our team."
When asked how he felt about Johnson's shock departure from the Warriors, Townsend went into bat for the Sharks' new recruit while questioning the Warriors handling of the saga.
"I was pretty shocked actually [with] how it all unfolded. The timing of the Warriors announcement, in terms of them saying there was no contract for Shaun beyond next season, while he was overseas, I thought was a bit odd.
"But it's crazy how rugby league works and I never thought that he would've ended up at the Sharks."
Having made the shift across the Tasman earlier in his career, the 27-year-old says Johnson will face a few challenges in his new surrounds.
"Any time you move country and to a different place that's foreign to you and you haven't had any experience of, is difficult. I can attest to that from when I moved to New Zealand.
"A new culture, new country, getting paid in a different currency, these are all things that Shaun's going to have to adapt to."
After enjoying celebrity status throughout eight years at the Warriors, Johnson will initially enjoy relative anonymity in Cronulla, but Townsend predicts that won't last long.
"He'll be able to walk down Cronulla mall and probably no one will notice him at this stage. But as he gets into the community and gets his name out in the [Sutherland] Shire, people will warm to him for sure."
However, he denies Johnson will have a difficult time dealing with the intense media scrutiny in Sydney, where league is the No 1 game in town.
"New Zealand media is pretty full-on, to be honest, but Sydney definitely is a rugby league hub.
"Obviously, a lot of focus is on the NRL here and especially with so many teams in Sydney, so he'll have to be on his best behaviour like the rest of us. But I have no doubt he'll handle the media and everything fine."
The Sharks are known for their uncompromising play and Flanagan has a similarly tough reputation, but Townsend believes their big-name recruit will thrive in his new environment and enjoy playing behind one of the biggest packs in the NRL.
"We've got a great front-row with [Andrew] Fifita and Matt Prior, and also, to have Aaron Woods come off the bench, we don't lose anything there.
"We've also got Paul Gallen and Wade Graham and a host of big names and a really tough pack, and that's something that I know drew Shaun into coming to us.
"Flanno is a great mentor to a lot of our players and knows how to get the group up for a game.
"He's coming into a team that's always prepared very well for games and that was one of the main points we put across to him before he came."
Johnson's legion of supporters can expect to get their first glimpse of him in Sharks colours during their preseason trials against Manly in Sydney on February 23, and Newcastle at Maitland on March 2.
The Sharks then open their 2019 NRL campaign with a Friday night away clash against the Knights at McDonald Jones Stadium on March 15.
