The Dockers are building an exciting young list following three years of heavy recruiting at the National Draft. Having already locked in some of their young talent, the news will further buoy Fremantle fans.
The deals see Erasmus and Johnson locked in until 2025, while Walker will remain until at least the end of 2024.
Perhaps the pick of the bunch, Erasmus made his debut in the Dockers' Round 3 win over rivals West Coast. The youngster impressed, collecting 18 disposals and taking four marks.
His debut had been touted all summer. He had impressed those inside the club since being taken with Pick 10 in the 2021 AFL National Draft.
Likewise, Walker has impressed since joining the club with pick 50 at the 2020 National Draft. In his debut season in 2021, he featured in 10 games, showcasing his line-breaking ability.
Speaking to the club's website, he was enthusiastic about the future.
"It's unreal, we are all pushing ourselves to be better and trying to get better in all aspects of our game," Walker said.
"We are a really young and exciting team, and juts getting better.
"It's great to learn and be a part of this club. I'm just living my dream playing football, so it's awesome."
Similarly buoyant was Erasmus following his debut.
"It was an unbelievable experience, you were in the crowds a year ago and now you are playing in front of them," he said.
"I was a little bit nervy coming through the race, but then all my mates were shouting in the stands, and it felt a bit more normal.
"In terms of my own game, I was satisfied with it, there is still a lot of work to improve on and I just need to learn each week, review properly and move on to the next game."
While Johnson hasn't yet had a clean run at it, his re-signing is just as positive. The classy midfielder was highly touted going into last year's National Draft.
Despite an ankle injury hampering his pre-season, Fremantle appear bullish on the youngster. The Dockers appeared quietly pleased when he slipped to them at Pick 21.
"The club has shown a lot of faith in me, and with my injury I haven't been able to play in my first year," Johnson said.
"The ankle is coming along quite well at the moment and I'm just starting to do a little bit of running now and upping my fitness.
"I've loved getting to know all the boys around the club. The coaches and staff have been super supportive of me, and I think the club is definitely heading in the right direction."
After a 2-1 start, the Dockers take on GWS at Optus Stadium on Saturday night.