Brown leaves the Cardinals having spent more than six seasons with the franchise, playing 77 games after being picked fifth overall in the 2007 Draft.
The Steelers decided to bring in the veteran offensive lineman after Mike Adams was dominated by Jared Allen during Sunday's defeat to the Minnesota Vikings in London, and coach Mike Tomlin revealed that he is excited about the move.
On Brown's prospective role in the team, ESPN quotes Tomlin as saying: "Obviously his ability to take in and learn information is going to be an element of that. Obviously [we're] excited about acquiring a veteran offensive lineman."
Tomlin also revealed that the decision to bring Brown into his side was due to below-par performances at left tackle so far.
"We've gotten below-the-line work and that's the reality of it. It needs to be above the line and we'll turn over any stone in order for that to happen," he added.
The Steelers released cornerback Isaiah Green to make room for Brown on the roster.