The Saints face Leicester in today's (18.04.21) semi-final and Hasenhuttl feels an appearance at next month's Wembley showpiece will be a positive conclusion to a mixed campaign.
The Southampton boss said: "We had some very good moments this season. We had been very high up in the table for a short term, then we had very big problems with injury.
"Maybe also because we were also focusing a little bit on the cup, selecting the strongest side for the cup games, especially in January and February, that cost us a few injuries.
"But a cup final can definitely turn things 360 degrees around, then it would be a successful season definitely."
A win would see the club reach their first final since 2003 and Hasenhuttl is aware of the significance of the famous tournament.
The Austrian coach said: "This FA Cup is a very traditional competition, the most known around the world, and this is the reason why everybody loves it so much I think.
"Sometimes (they love it) more than a few managers at the moment because the Premier League has a very high level in our daily work and we are always getting called (out) on how much we have won in the Premier League, on how many points we have.
"The FA Cup is then a little bit in behind, but I think the fact you have three or four weekends where you play this cup is something unique in all the leagues around Europe, that you play the cup at the weekend.
"It shows how important the cup is here for the people in this country and should be for us."