Neill, who joined Watford on a short-term deal in February, was excited about getting some games under his belt as he looks to force his way back into the Socceroos squad for the 2014 World Cup.
"Having played with the manager during our Blackburn days, I know the style of his team's play will reflect that of his playing career and that is a competitive, hard-working and energetic style.
"I am looking forward to joining my new team mates and working hard to earn their respect and help them have a successful end to the season."
Neill, who has played 96 times for Australia, added: "I made a very deliberate decision to come back to England to give myself that chance that I need.
"I'm hungry to do what is necessary to be on that plane, I know I can be a part of it and add value to the squad."
Neill could make his Doncaster debut when the 20th-placed side head to Elland Road to take on 14th-placed Leeds United on Saturday.
For breaking stories and all the great banter like us on Facebook: facebook.com/tribalfootball