The 26-year-old was born in Doncaster and began his career at Sunderland before spells with Norwich and Preston.
Brown enjoyed a stint on loan with Doncaster during the 2003-04 campaign, making 22 appearances and scoring 10 goals.
And he is delighted to join O'Driscoll's side on a permanent transfer this time around.
He said: "I spoke to Sean last week and it's been ongoing since but it was easy to make the decision to come back to Rovers.
"Phil Brown indicated he wanted me to stay but I wanted to see what was out there and as soon as Rovers came in I knew it was the only club I would leave for."