Beltre will be activated from the disabled Friday, the first day he's eligible to return.
"He's ready to go," manager Ron Washington said. "It means a lot. He's our leader. He's our guy. We'll be happy to have him back finally."
Beltre has not played since April 8 because of a strained left quadriceps muscle.
Beltre hit .315 with 32 home runs and 92 RBIs last season. Over the past three seasons he has a combined 98 home runs and 299 RBIs.
When Beltre returns to the lineup, he should provide protection for first baseman Prince Fielder, who has been intentionally walked nine times in April, an American League record for the month and a Rangers record for any month.
Harrison will come off the disabled list and make his first start in over a year in the finale of the Rangers' three-game series against the Seattle Mariners, Washington said Wednesday.
"I'm excited to finally get back here," Harrison said. "The way it went last year, I didn't think I'd ever pitch again."
Harrison hasn't made a big-league start appearance since April 6, 2013. He underwent surgery to repair a herniated disk in his lower back on April 23 and, eight days later, had surgery on a different part of the disk.
He made three rehab starts in July and August, but was shut down for the 2013 season after experiencing numbness in his left hand during the third rehab start. He had surgery yet again on Sept. 9, this time on his right shoulder because of Thoracic Outlet Syndrome.
"It means a lot," Harrison said of his return. "A lot of hard work. A lot of people along the way helped me to get where I am."
Washington said he initially planned to have Harrison start Friday at Seattle, but he juggled his rotation to make sure that neither Harrison nor right-hander Colby Lewis would have to pitch when the Rangers play two interleague games at Colorado on May 5 and 6.
Lewis, who had season-ending hip surgery last year on Aug. 22, made his first start of the 2014 season on April 14.
"Don't want them hitting, so we had to adjust," Washington said.
Left-hander Robbie Ross Jr. will start Friday night against Seattle, and Lewis will start Saturday's game against the Mariners. When the Mariners return home for a three-game series against Oakland, Yu Darvish will start on Monday, Martin Perez on Tuesday and Ross on Wednesday.
Harrison threw bullpen sessions Monday and Tuesday and plans to throw again on Friday.
"Everything is good," Washington said. "Mind is in the right place. Ready to compete."
Harrison went 18-11 with a 3.29 ERA in 2012. He was the Rangers' Opening Day starter in 2013 but made only two starts that season.