However, Millers boss released the winger at the end of last season after struggling to make the Millers line up.
Today he signed a 1 year contract at the County Ground, with the option of a second year depending on appearances.
Monkhouse told the Swindon Town official website, "I am really happy to be here and the people at the club have made me feel really welcome. I just can't wait to get started,"
"As soon as Dennis and Gus took over I knew it was where I wanted to be. Having spoken to them both they said they might play some part as well, so that would be fantastic for me in terms of players to learn from." he added