The Orioles are looking for a veteran starter to help stabilize their rotation, and Arroyo is one of baseball's most consistent pitchers. He has made 32 or more starts and thrown 199 or more innings in each of his past nine seasons. Four of his past five years he has posted an ERA of under 4.00 with the Reds.
The Los Angeles Dodgers and Arizona Diamondbacks also are reportedly hotly pursuing Arroyo.
The Orioles already have 60 players set for major league camp.
They added another player to their system Thursday, signing first baseman-corner outfielder Matt LaPorta, a former 2007 first-round pick of the Milwaukee Brewers, to a minor league deal without an invitation to major league camp.
LaPorta, 29, last played in the majors in 2012 with the Cleveland Indians, batting .241 with one homer in 60 plate appearances. A former Florida teammate of Orioles reliever Darren O'Day, LaPorta had hip surgery before the 2013 season and didn't return to the majors.