Tyson has scored four goals in the last two seasons
Former Nottingham Forest striker Nathan Tyson has completed his move to Derby County on a free transfer.
turned down the offer of a new deal at Forest
before agreeing a three-year deal with their East Midlands rivals.
"Derby County is a club with big ambitions and I want to be part of it," he told the Rams' website.
"I'm ambitious myself and want to play at the highest level, I think we can achieve that here."
Rams boss Nigel Clough added: "Nathan is a player of proven quality at this level and is someone who was right at the very top of our wanted list.
"His pace is electrifying and scares defenders to death.
"We see Nathan playing more as a centre-forward, his goalscoring record at Wycombe was very impressive and we'd like to see him repeat that here."
Tyson scored 44 goals in 87 appearances at Wycome before joining Forest, where he netted 42 times in 213 games in a five-and-a-half-year stint.
He initially joined the Reds on loan from Wycombe Wanderers before completing a £675,000 move in January 2006.
Tyson is no stranger to Derby supporters following an incident at the end of
Forest's 3-2 victory over the Rams in August 2009.
After the final whistle, he ran across the pitch waving a corner flag.
He was confronted by Derby opponents shortly before a large group of players and staff from both teams became involved in a tussle.
Both clubs were fined for the fracas and Tyson was handed a two-game suspension and a £5,000 fine