Here's the official announcement:
Czech Republic international Tomas Rosicky has today joined Arsenal Football Club from Bundesliga side Borussia Dortmund on a long-term contract for an undisclosed fee.
Attacking midfielder Rosicky, 25, who has made 31 appearances in the UEFA Champions League for Borussia Dortmund and Sparta Prague, secured World Cup football for the Czech Republic this summer by scoring the winning goal in the decisive qualifying play-off second leg against Norway last November.
After joining Borussia Dortmund in January 2001, Tomas won the Bundesliga and reached the UEFA Cup Final in his first full season with the club (2001/02). He also enjoyed success with Sparta Prague, where he won back-to-back Czech Republic league titles in 1999 and 2000.
Rosicky made his international debut aged 17 and represented his country at the 2000 and 2004 European Championships. Tomas was also recognised in his home country by becoming the youngest ever winner of the Czech Player of the Year award in 2001 aged 20, and he went on to repeat the honour the following season.
Manager Arsène Wenger said: “We are delighted to welcome Tomas to our squad. He has great technique, skill on the ball and sharp passing. Tomas has good experience at all levels for club and country, and we look forward to welcoming him to Arsenal after what will hopefully be a successful summer for him at the World Cup.”
New Arsenal signing Rosicky said: “I'm really happy to be here at Arsenal, it is a great day for me. The team showed its strength recently in the Champions League and it has big potential with a lot of young players, I think we can be even better next season. This is the best club in Europe and I will give everything for Arsenal.”
Rosicky will join up with his new team-mates after competing in this summer's FIFA World Cup.