In six innings, Fernandez struck out nine, matching the team mark previously set by Josh Beckett against Montreal in 2004.
"We got it all tonight, for sure," manager Mike Redmond said. "Jose set the tone."
The fact Fernandez showed sign of improvement is not startling. What was encouraging for the Marlins is their offense responded with plenty of run support. Consider last season, Miami was shut out in its first two games at Washington and scored just one run in getting swept in three games. The Marlins scored their most Opening Day runs Monday since they beat the Nationals, 12-6, in 2009.
A year ago, the Marlins finished last in the Majors in runs scored, and four times they scored as many as 10 runs in a game. On Monday, the bats got going off Rockies lefty Jorge De La Rosa.
Marcell Ozuna homered and had three hits, while Casey McGehee had two doubles and matched his career high with four RBIs during the 14-hit attack.
"That's where we struggled as a team last year, getting the run support," Fernandez said. "Obviously, these guys can hit. I said it when we went to Spring Training. I think we have a good team. The relationships are amazing. We're always joking around, it's fun. It's so much different than last year."
Carlos Gonzalez's sixth-inning home run was the lone run Fernandez allowed. Miami touched up De La Rosa for five runs in 4 1/3 innings.
"You always want to win the opener," catcher Jarrod Saltalamacchia said. "You want to win at home. Jose went out there and really energized the lineup for us."
The night was memorable for many reasons for Fernandez. At 21 years, 243 days old, the right-hander became the youngest Opening Day starter in Marlins history. He's also the youngest Opening Day starter in the big leagues since Felix Hernandez, who was 20 years, 359 days old for the Mariners in 2007.
With a fastball that reached 99 mph and some dazzling breaking pitches, Fernandez is tough to beat anywhere. But at home, he is perfect -- improving to 10-0 with a 1.21 ERA.
Adding to the emotions was the fact Fernandez's grandmother, Olga, was on hand, along with his mother, Maritza. Olga, who still lives in Cuba but has been granted a visitation visa, had not seen her grandson pitch in person since he was 14.
"It is very hard for me to even describe what this means to me," Olga said in a statement delivered by the Marlins. "It really does mean the whole world to be here and see him pitch for the Marlins in a Major League game. I have not seen him pitch in a game in person since he left Cuba, and to be here tonight is the ultimate feeling of all the emotions -- happy, proud, love."
On the day he pitches, Fernandez typically gets antsy. The 21-year-old woke up about 4 a.m. ET, went back to sleep and opened his eyes again at 6 a.m. He finally rolled out of bed at 8 a.m., and made sure everybody else in his house also was awake.
"I woke up everybody," Fernandez said. "I got here around 3, and I watched the Pirates and Cubs."
Fernandez certainly gave everyone plenty to cheer about. So did the rest of the Marlins. Ozuna's home run gave Miami the lead in the third inning, and the five-run fifth broke the game open.
The first hit for the Marlins in 2014 set off the home run sculpture. De La Rosa breezed through the first two innings, striking out four of the first six he faced. But to start the third, the lefty fell behind in the count to Ozuna, who finished a triple shy of the cycle.
"I was excited. It was my first Opening Day," Ozuna said. "I tried not get too excited, and [just] play the game right."
In the five-run fifth, Adeiny Hechavarria ripped an RBI single to center and Giancarlo Stanton had an RBI infield single. The crucial blow was delivered by McGehee, who laced his three-run double down the third-base line off Wilton Lopez.
The Rockies responded with their lone run, which came on Gonzalez's monster blast off Fernandez with one out in the sixth.
"I just put a good swing on the ball," Gonzalez said. "It was a mistake. He put it right down the middle and I took advantage. When you get a pitcher like that, you can't miss those opportunities."
Jeff Baker added a sacrifice fly in the sixth inning, and Christian Yelich, Stanton and McGehee added RBI doubles in the eighth.
After losing 100 games last year, the Marlins feel they have are moving quickly toward respectability. Fernandez hopes the South Florida fans take notice.
"I hope so, because this team is special," Fernandez said. "I see that. Not because we scored 10 runs today. We're going to lose a couple, but this team is going to fight. That's the only thing we want. We want to go out there and fight."