Astros manager A.J. Hinch announced the move after Tuesday's 5-3 victory over the Angels. The team has not announced who will be promoted to replace Marisnick on the roster.
"We want it to be a short stay in the minor leagues," Hinch told reporters, according to MLB.com. "He needs to get some at-bats. He hasn't really been right for most of the year. The swing-and-miss has been a struggle for him. He's a really good player that hasn't quite gotten on track.
"I think it's been piling up on him in the last few weeks. He needs a run of at-bats he's not going to get here over the next 10 days or however long he's down there to get back to being a contributor again."
Marisnick is batting .141 with three home runs and seven RBIs and is mired in a 6-for-53 slump. He has struck out 41 times in 85 at-bats and has struggled to find playing time in Houston's crowded outfield that includes George Springer, Josh Reddick, Derek Fisher and utilityman Marwin Gonzalez.
"In the sport we play, you don't perform and you get sent down," Marisnick said. "It's an opportunity to go down and get at-bats and get it right. It's no secret I've been struggling. I'll take this opportunity to take the at-bats and try to get going."
Marisnick, 27, emerged as a key contributor on Houston's World Series-winning team last season, when he batted .243 with a career-high 16 homers in just 259 at-bats.