The 30-year-old, who plays high school Glee Club director Will Schuester on the US show, said that the programme straddles between comedy and drama.
He told TV Guide: "There's a certain amount of camp involved in the show. The reason we get away with so much stuff is because we don't take ourselves too serious, and that's going to keep going.
"But Glee rides a great line where there's this amazing energy but [it] also has these deep emotional moments as well."
Morrison also explained that he and co-star Jane Lynch are permitted to improve many of their scenes together.
He added: "We go in with our lines, but with Jane and I, they really let us go. A lot of what they keep for the scene is our ad-lib. We have a lot of great stuff together.
"Those scenes are so much fun to do, except I have to try not to laugh."
It was recently reported that Kristen Chenoweth and Victor Garber have joined the cast of the musical comedy series.
Glee debuts on US TV tonight, after a sneak preview for the pilot premiered on an American Idol episode earlier this year.