The Japan star became the first Asian player to score a treble in the Barclays Premier League as he launched United towards a 4-0 win over Norwich at Old Trafford on Saturday afternoon.
It was the stand-out contribution to what was largely a drab affair and enough to take United 15 points clear of Manchester City in the title race.
Ferguson feels there is much more to come from Kagawa, whose only other goals this term came prior to a knee injury sustained against Braga in October that kept him out for over two months and hampered progress following a summer move from Borussia Dortmund.
"It was a brilliant day for him," said Ferguson.
"He is a good finisher. His second goal was composed and intelligent, his last was brilliant.
"He missed that period of football in October and November that set him back a bit.
"He is gradually getting his form back but next year he will be far better, you will see a really good player then."
Strangely, Kagawa's heroics may not be enough to get him a starting berth against Real Madrid on Tuesday.
Rio Ferdinand and Rafael were left out with that game in mind, whilst Ryan Giggs was also denied a 1,000th senior appearance in readiness for some meaningful contribution against Jose Mourinho's men.
"It will be a fantastic night," said Ferguson.
"You are talking about two of the greatest clubs in the world.
"Emotions will be high and I am sure it will be a tremendous match.
"If we can get a blank against us on Tuesday we would go through.
"But I think both teams will score. I just hope we get more than them."
Norwich boss Chris Hughton believes United will progress, just as he thinks - with 10 games remaining - the Red Devils are now sauntering towards a record 20th championship.
"What you have with United is a team that is playing well enough," he said.
"If you look at their recent run, they are winning games comfortably.
"At the moment you don't see any other outcome than them winning the title.
"Offensively, when they are at their best, United are outstanding.
"Their offensive options are the reason why they have had such a good season and are so far clear in this division."
Nevertheless, Norwich could feel somewhat aggrieved at the final scoreline given they were only a goal down heading into the last 20 minutes, with United barely getting out of second gear.
It was then that Wayne Rooney made his decisive contribution, setting up two for Kagawa before belting home his 14th of the season in the final minute.
"It was good to get Wayne the full game," said Ferguson.
"He scored a goal, which is always important for a striker.
"It will help his confidence."
And with a break now for both Champions League and FA Cup combat, Ferguson's side could hardly be better placed, even if he would prefer not to talk about it in such terms.
"The best way for us to handle it is to win our games," he said.
"If we win our next game, then the next, we don't need to look back.
"There is a great atmosphere in the dressing room. That is helping us.
"No matter what comes up, they are relishing it."