Riggott was released by the Rams at the beginning of January and he has been training with Albion in recent days.
"Sometimes things just fall in your lap. He's been released from Derby and he's wanted a place to train. He's enjoyed his time (with us) and we've managed to put together a deal that suits both parties," said Burton boss Paul Peschisolido.
"He's a great addition, a player of his experience. He's played at a much higher level throughout his entire career. He's got a lot of quality."
Riggott began his career at Derby and went on to make 91 appearances for the Rams before moving to Middlesbrough where he played over 100 games. Spells at Stoke and Cardiff followed before he rejoined Derby in 2011.
Shortly after signing the deal with Albion, the 31-year-old said: "I'm just excited and looking forward to playing some football. It's been a difficult few years for me with injury but hopefully those problems are behind me now.
"I'm grateful for the opportunity to come and try and prove to myself as much as anything that I can still play. There's plenty more football to play this season and I'm looking forward to playing as many games as I can."
