The Owls are assured a mid-table finish while Cardiff travel to Hillsborough needing a point to guarantee their place in the play-offs.
Grant knows his side face a tough task on Sunday but is hoping they can give the fans cause for optimism ahead of the next campaign.
"It's important for us to perform in front of a big crowd and give something to warrant them coming back next season," Grant told the club's official website.
"Things are improving in and around the club and there has certainly been progression for the fans to see on the pitch so the foundations are down for next season.
"It is up to us to make sure we finish on a high. It will be a tough game and one that we're looking forward to and we want to come away with a positive result."