Rodwell played his last Sunderland game 10 months ago and has moved to Mowbray's side in an effort to get his career back on track.
The midfielder failed to impress at both Manchester City and Sunderland, though Mowbray has high expectations for the 27-year-old.
"I like his personality. We have seen the lack of game time in the last year or two and we know about the injuries. But he went for £15m at one time to Manchester City and he has played for England. I just want to see the lad on the grass.
"If he has anything about him he has to try and break into our team. And if it works out, we have a pretty good footballer. I don't sign players without doing background checks. It is something I have done for 15 years. His personality is not a problem. His robustness, we will have see.
"He is at the stage of his career that he has to understand he is mature. I have footballers here who play with knocks, play with sore knees, have treatment after every game and go out on Saturday and run a marathon. That is what footballers have to do.
"If you want to play and earn your corn in font of thousands, that is what you have to do. Jack has the opportunity to put on a Blackburn shirt and make a name for himself."