The Houston Astros said Wednesday that Norris will start on March 31 in the opener against Texas Rangers on March 31.
The Astros will host Texas in their first game since joining the American League in that Sunday night opener.
"You don't have an opportunity like this all the time, to go out there and throw the first pitch of the season," Norris said. "When I say it's a childhood dream come true, that's truly what it is."
The 28-year-old righty was 7-13 last year. He is 2-0 with a 5.52 ERA in four spring training starts.
Norris will be the Astros' fourth different opening-day starter in four years.
"I've always been kind of the 'B' player who's been chasing the lead dog, but I'm excited," he said. "This is something I've always wanted. It's something I talked with Roy Oswalt about back when I was a younger player."
"It's an honor that you really want to go out there and prove to your team and your city that you've earned it. I'm hoping this is one of many, but I'm going to take this one and enjoy it," he said.
Lucas Harrell will start the second game for Houston against the Rangers on April 2.
"He's earned it. He's been here longest," Harrell said of Norris' assignment. "He's pitched well, he's proven he can do it."
The Astros said pitchers Jordan Lyles and John Ely have been optioned to Triple-A.
After going 3-2 in his last seven starts last year, Lyles had been expected to be in the Astros' starting rotation. But he has had a dreadful spring, giving up 36 hits in 11 2-3 innings and posting an 0-3 record with a 17.74 ERA.
"The reality is if Lyles were a 10-year veteran, it might be a little different," general manager Jeff Luhnow said. "But he's 22 years old, he's got to earn his spot, and frankly we feel like he needs to go down there and prove he's the guy that we know he is."
"But I think it's just a formality. He'll be back," he said.
Two spots remain open in the Houston rotation. Veteran left-hander Erik Bedard, whose spring was set back by a minor injury, remains the leading candidate for one spot. Alex White and Brad Peacock are competing for another slot.