The 23 year-old right winger has the option of a third year with Steve Evans men after leaving Bury, and joins for an undisclosed fee which is believed to be around £150,000.
Worrall told the club website themillers.co.uk: "I spoke with Joe Skarz who I knew at Bury, looked around the stadium and knew it was a great move for me.
"Looking around it was a lot different to what I am used to. I spent five years at Bury where there were many ups at the start but last season was a struggle. As soon as I spoke to Rotherham and learned about what the manager had planned I jumped at the chance to sign.“I am an honest hard working player, and hopefully the club can improve me as a professional,” he added. “I’ve looked at the first month of the fixtures and after playing in League One for a few years I know it will be tough, but I don’t see any reason why we cannot go into those games and get some good points. “We will be a surprise package to an extent to some teams in this division who won’t have played Rotherham for a few years and hopefully that may fall in our favour."
Boss Evans earlier confirmed he expects a further two deals fo be finalised shortly, whilst he is also in talks with an Icelandic International. The club are yet to confirm the expected signing of forward Danny Hylton.
The Millers squad return to pre-season training next Wednesday.