Viktor Kolar claims that the midfielder has already undergone a medical and will sign a six month loan deal which will allow him to play against Scunthorpe on Saturday.
"Chelsea wanted Jiri immediately but CSKA were against it, so the loan was agreed at first," said Kolar.
Jarosik is reported to have said: "I am delighted - it is the greatest chance of my life."
Jarosik will make up for the midfield shortfall as a result of Scott Parker's broken bone injury - but the Czech star, 27, won't be able to play in the Champions League, having already played for CSKA this season in the competition.