Miller went 0-for-3 in his debut, but drew a walk, drove in a run, stole a base and made several key defensive plays.
"Just getting out there was a big thing, just getting some at-bats and getting to play and then making some adjustments from there," Miller said. "It was so much fun just getting out there and running around and playing. It was pretty sweet."
Count manager Eric Wedge as one of those impressed with Miller's debut.
"I thought he was outstanding," Wedge said. "I thought he had a solid first game. First ball came to him, that's always a plus, get that out of the way. The play going to foul territory, he went a long way to get that ball. He made the dive, stole a base, got on base with a walk, went up there ready to hit. It was a solid first night."
Additionally, converted second baseman Dustin Ackley made his Major League outfield debut Friday night after being recalled from Tacoma on Tuesday, going 0-for-4.
Infielder Carlos Triunfel, 23, was optioned back to Tacoma to make room on the 25-man roster. Triunfel hit just .083 in 24 at-bats while receiving limited playing time.
Infielder Alex Liddi, 24, was designated for assignment to open a spot on the 40-man roster. Liddi hit .208 with six home runs and 16 RBIs in 61 games with Seattle over parts of the past three seasons and was batting .263 with 11 homers and 53 RBIs for Tacoma this season.
The Mariners now have 10 days to trade, release or outright Liddi's contract.
Wedge said Miller will be given an opportunity to show what he can do at shortstop and the way he'll be used will be similar to Zunino, who has seen most of the catching duties since his promotion on June 11.
"We're going to take a look at him," Wedge said. "He's been playing fantastic in Triple-A and made a great impression on us in Spring Training, very similar to Zunino, so we feel like it's a good time to take a look at him."
Miller, who grew up in the Orlando, Fla., area, said it's been his dream to play in the Majors "ever since I can remember" and he's still having to pinch himself at the opportunity.
"It's funny, because every year we were the Mariners in Little League," he said. "Every single year, because of Ken Griffey Jr. and everything. This is just surreal."
The Mariners are looking to improve their offense and Miller has hit at every level of the Minors in his quick rise since being a second-round Draft pick out of Clemson in 2011. He hit .334 in 219 games over his three Minor League seasons, including .356 with six home runs and 28 RBIs in 26 games for Tacoma since being promoted from Double-A Jackson this year.
Veteran Brendan Ryan has been the regular shortstop the past three years and is one of the premier defenders in the Majors, but has a .217 average in 331 games for Seattle and is batting .196 this year on the heels of a .194 season in 2012.
"He was good, he's a pro," Wedge said of his conversation with Ryan after the move. "I told him to come to the ballpark ready to play every day and we'll see how it plays out."
The left-handed-hitting Miller was selected on Wednesday to play in the upcoming Futures Games during the All-Star festivities in New York on July 14, though he won't be eligible to play in that game if he's still on the Major League roster at that time.
Miller hit .415 in 14 games for Class A Clinton in 2011 after signing with the organization, then batted .339 in 97 games for Class A High Desert and .320 in 40 games for Jackson last year. He hit .294 in 42 games for Jackson this year before getting moved up to Tacoma, where he reached base in all 26 games he played.
Miller caught Wedge's eye in Spring Training, when he was one of the last players cut after a strong camp.
"He's a very mature young man," Wedge said. "He looks to have tremendous perspective and obviously his baseball ability sticks out, as well. He's a complete player, that's why we kept him around the entire camp."
Miller said that experience helped carry him into this season.
"I think the biggest thing was all the things I learned in big league camp in the spring, I just wanted to kind of put that into practice every day," Miller said. "The stuff I picked up from Raul [Ibanez] and [Kyle] Seager and Brendan, it's definitely helped. Just the way they go about their business and the confidence is huge. So I just wanted to kind of put that into practice."