The 21-year-old has agreed a one-year deal at Valley Parade and could feature in Tuesday's League One game at MK Dons after getting international clearance.
Rabiega began his career with Hertha Berlin and moved to RB Leipzig in 2013.
"He's come in on trial and done well - we feel he has something we could work with," Bantams boss Stuart McCall told the club website.
"We are still in the market for another more experienced forward but Vincent could give us an extra option."
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Bradford City have completed the signing of German-born former Poland youth international Vincent Rabiega.