The 26-year-old, who was available on a free transfer after deciding to end his three-year stay at Hillsborough during the summer, becomes the Millers’ 11th signing of the close season and joins former Wednesday team-mates Joe Mattock and Lewis Buxton at the club.
“It is fantastic news that has reached me in Scotland this morning that Chris Maguire has become a Miller,” Rotherham boss Steve Evans told the club’s official website.
“This young man is a player I have admired since his days at Aberdeen and he was a lad that was on my targeted list of players at the end of last season.
“We have had to be patient as we gave this young man the time to speak to a number of Championship clubs who wanted him to join them.”
Maguire began his career at Aberdeen in 2005 and went on to make 131 appearances, scoring 16 times, before making the move south of the border to Derby County in 2011.
He joined Wednesday only a year later, following a loan spell with Portsmouth. Maguire, capped twice by Scotland, became a firm favourite with the Wednesday support during his time with the club, which produced 19 goals in 92 appearances.
And Evans believes the versatility of Maguire, who can operate as a forward or in the midfield, will be a benefit for his squad ahead of their second season back in the Championship.
“We love a player who can play in more than one position, and we all know that Chris Maguire can play as a striker or indeed a wide position, he has great qualities in both departments,” the Rotherham boss added.
“He joins what is already a talented squad and in the next week or so I would envisage that same squad maybe strengthened further.
“This has been a summer transfer window that has seen us with a very specific targeted approach for players. The focus, attention to detail, player references and what they will add to the Millers has been at the forefront of our thoughts in everything that we have done.
“Once again I must thank my chairman Tony Stewart for his continued and everlasting support.”