The Zimbabwe international has agreed a one-year deal with Rovers, with an option of a further year at Ewood Park following spells at Portsmouth, Manchester City and Sunderland.
The 32-year-old has made just 26 appearances over the past two seasons, due to a combination of injuries and failing to get much playing time at Eastlands and the Stadium of Light.
Ewood Park boss Sam Allardyce decided to give Benjani his chance by recruiting the striker before the end of the summer transfer window.
Now Benjani is out to prove that he can still rediscover the form that made him such a threat during his days on the South Coast.
He told the Lancashire Telegraph: "You need to work hard and repay any team that gives you an opportunity. I am no different and I want to make sure Sam Allardyce doesn't regret giving me my chance.
"I'm happy to be here and I will try and fight hard. It is not going to be easy to break into the team because there are some players who are playing really well at the moment. It's going to be hard for me.
"I am here at Blackburn because they approached me and they were the only club who wanted me. I wanted to stay in the Premier League so I came here.
"My plan B was to move away from here. I had a couple of clubs who were interested but not here in England.
"As a striker you always want to score goals as much as you can. I know I will have to fight hard to score goals here.
"Of course there are a lot of good players here, it is like that at any club, and all we can do is fight hard for a place and take your chance."
The striker is currently working on his fitness and hopes to thank Sam Allardyce by making an instant impression at the club.
"I am happy to be here and happy they gave me the contract. Of course I had to convince the manager because some people were saying things about me not being fit enough," he said.
"I need to come here and prove myself and hopefully that is what I will do. As far as I am concerned I am fine, I think I am okay and that is why I am here."