The burly 23-year-old is yet to play a senior game in 2008 after starting the year in the VFL.
Johns kicked two goals in last year's Anzac Day encounter, which the Magpies won by 16 points.
"He’s played a number of weeks in the VFL so he’ll come into the line-up," Knights said of Johns.
"At this stage we haven’t decided which player will miss out, but Johns will definitely come into our 22."
Knights also made a strong indication that Johns wouldn’t be the only inclusion for Friday's match and hinted that club great James Hird could play some part in the plans.
"Whether he’ll be involved on Friday, we’ll leave that to Friday," Knights smiled.
"But someone of the ilk of James and the legacy he’s left and the iconic figure he is, you never know, we may get him involved."
Knights also concerned about the form of Bombers skipper Matthew Lloyd, who was kept goalless against the Saints last week.
"I’m not concerned about Matthew Lloyd at all," he said. "Matthew didn’t play much of the pre-season, him and Dustin Fletcher. He’s had some decent games this year. He’s had some games where, because he’s got a lot of pride, he’d like to be better.
"It’s all about him playing his role as captain and for the team. It’s not about Matthew Lloyd kicking five, six, seven [goals] a week. It’s about him contributing and us developing as a team and getting better."
Collingwood has highlighted its bruised and battered state after the defeat to North Melbourne at the weekend and, after consecutive six-day breaks, there is confirmation that captain Scott Burns is struggling to be fit for Friday.
However, Knights is dismissive of any such talk.
"I’m not sure Collingwood are too beaten up, to be brutally honest," he said. "They were one kick away from beating the Kangaroos last week so they’re in good shape. Let’s not forget that."
It will be Knights' first Anzac Day match as coach – something he's keenly awaiting.
"To be a part of it on Friday as a coach is something I’ll always treasure and something I’m very proud of," he said. "Kevin Sheedy and James Hird had such a magnificent foundation with this day and have left a great legacy.
"I just really feel proud to be following in those footsteps."
However, the magnitude of the occasion does bring some added pressure.
"No doubt it does," he confirmed. "With Kevin and James, the day was partly about them and obviously about the significance of Australian history and what it [Anzac Day] has meant to this country. I’m wonderfully proud to be involved and I know our players are very much looking forward to the occasion.
"There’s heaps at stake, no doubt about that. We know as a club where we’re headed. We’ve got a direction, we’ve got a plan and I guess it’s a new dawn for the Essendon Football Club … I don’t know whether it will shape the season but it’s great experience for our young players who want to aspire and play on those big stages."
Knights also acknowledged midfielder Adam Ramanauskas, for whom the Anzac Day clash will be a special occasion after his inspirational return from cancer last year.
"For a player like Adam who’s been through such an enormous challenge personally with his life, to run out on Friday is fantastic," he said.
