The 32-year-old spent seven years with the Blues but left on a free transfer following the expiration of his contract and ultimately joined Arsenal on a three-year deal.
The versatile attacker has struggled to make his mark for the Gunners, failing to score in 26 appearances in all competitions and registering just four assists.
Willian has said that he would have stayed with Chelsea had they offered him a three-year deal and has admitted that it was "difficult" to move to the Emirates Stadium.
"It was difficult to make that decision. Because... the rivalry between the two clubs is very big. It was well thought out... talking to my wife and even the agent many times," Willian told UOL Esporte.
"I didn't leave the club with a fight, I left the doors open. Everyone knew the conditions, I really wanted to stay. We ended up not finding an agreement, I ended up asking for three years, Chelsea wanted to give two, and everyone knows this story. That's why I ended up leaving."
Willian has not started for Arsenal in the Premier League since the middle of December.