The 41-year old Ramirez, who hasn't played in the major leagues since 2011, served as the designated hitter and batted cleanup for the Express. He also drew a walk.
The Express picked up a 4-0 victory before 8,910 fans at Dell Diamond, many of whom serenaded Ramirez with encouraging "Manny, Manny" chants throughout the night.
"It was awesome," Ramirez said. "When you get all the fans cheering for you and you're just trying to get a good at-bat."
Speaking at a mid-afternoon news conference before the game, Ramirez looked relaxed -- albeit a little tired -- and seemed very confident he can get back to the major leagues.
"I can do it," Ramirez said. "I've been thinking about this day almost for a week. I'm just like a little kid going back and playing the game that I love."
Ramirez said after the game he was nervous as he made his way to the plate for his first at-bat. Wearing jersey No. 99, Ramirez ripped an opposite-field single to lead off the bottom of the second inning, swinging at the first pitch from Omaha starter Yordano Ventura, who at 22 years old is the Kansas City Royals' top pitching prospect.
Ramirez went after the first pitch from Ventura in his second at-bat in the third inning, this time with a runner at first, and grounded out to shortstop. Ramirez had his best matchup of the night against Ventura in the fifth inning. With a runner at second and two outs, he swung and missed at a changeup, then was late on a 98 mph fastball.
The slugger's most interesting at-bat came in the eighth inning against Omaha reliever Michael Mariot. He worked the count, fouled off a high fastball, and, with chants of "Manny, Manny" the loudest they had been all night, he took a pitch low for ball four.
Ramirez then was replaced by a pinch runner. He saw 13 pitches on the night, including seven in his last at-bat.
"I have to make some adjustments," Ramirez said. "I haven't played in two weeks and you face a guy that throws 100 [mph]. I just went up there and tried to get comfortable and get a good pitch to hit."
Ramirez said he wasn't going to watch video of his at-bats, which he's known to do religiously, after his first game back.
"I don't want to put a lot of things in my mind," Ramirez said. "I just want to go out there and enjoy it."
The 12-time All-Star has no timetable for how long it will take to let himself and the Rangers know that he is ready to face big league pitching.
The Rangers suffered a blow Sunday when 37-year-old designated hitter Lance Berkman was placed on the 15-day disabled list with an injury to his hip or lower back. Ramirez said knowing Berkman is sidelined won't make him rush things.
Sporting what appeared to be a mullet-mohawk haircut with several short dreadlocks, Ramirez said before the game he feels as if he's in good shape.
"I feel good," Ramirez said. "I feel much better than I did before. I'm more confident and I'm smarter."
Ramirez's hitting credentials suggest he may be able to pull off his comeback attempt, even at 41. He is a career .312 hitter with a .411 on-base percentage, a .585 slugging percentage and 555 home runs.
Ramirez appeared in five games for Tampa Bay in 2011, then retired before official word came down of a 100-game suspension for a second positive steroids test. When he wanted to return in 2012, Major League Baseball and the players' union agreed he would serve a 50-game suspension. He played in the minors for Oakland in 2012 before asking for his release last June.
The Rangers have been told that Ramirez has completed all the suspension time that was needed to return to the major leagues.
Ramirez will play for the league minimum, a prorated amount of $500,000, and will donate the money to a charity and his church. He didn't know which charity he wants to give the money to as of Sunday. His big concern as he starts playing games is staying healthy, and he has not targeted a particular area of his swing on which to work.
"I don't even think about it," Ramirez said. "I just go out there and practice and try to have fun and enjoy it. I have to get used to the pitching here. I don't have anything to lose and everything to gain. I'm happy."
Todd Wills covers the Rangers for ESPNDallas.com.