The 34 year-old goalkeeper joined Strasbourg from Bordeaux after they entered administration in preseason.
On Chelsea's presence at Strasbourg, Johnsson told Fotbollskanalen: "The club is in good balance and has financial strength considering the collaboration with Chelsea. A lot of new players have come in, so it's a hungry, young and talented team. It's a very exciting project and it feels great with all the coaches and everything around."
Along wth Johnsson, Chelsea keeper Djordje Petrovic has arrived on-loan.
"I spoke to the coach when I arrived, and then he said that he will not have a first and second choice. He wants to play with those who he thinks can win the game for us next weekend. I therefore see opportunities to play. I'll take the fight and do my best and then we'll see how it goes. I have been involved in it before and know how to deal with it, at the same time I usually handle it well."