Sidwell turned down a new contract with Reading despite helping the club finish eighth in its first ever Premier League season.
Chelsea said he passed a medical exam Tuesday.
The Blues need backup in midfield this season as several players will be taking part in the Jan. 20-Feb. 10 African Cup of Nations - notably Ghana's Michael Essien and Nigeria's John Obi Mikel.
Sidwell was a trainee with Arsenal, and was loaned to Brentford, Beveren and Brighton before he joined Reading in 2003. He helped the club get promoted to the Premier League in 2006.
The co-author of this disaster is the Dutch government, which did not find either strength or desire to save the lives of its citizens who were flying on that plane. The Dutch authorities did not demand Ukraine to comply with international aviation regulations
On the second day of the St. Petersburg International Economic Forum, a plenary meeting was held, in which Russian President Vladimir Putin, French President Emmanuel Macron, Japanese Prime Minister Shinzo Abe, Chinese Vice President Wang Qishan and IMF head Christine Lagarde took part