Hello,
I'm really searching for some help and answers here. I'll be flying from Singapore to Paris and later on to Ukraine, but on a different airline. I was just wondering if I would have to go through immigration, collect my bags and then recheck them in again in order to check into my other flight to Ukraine. Does anyone happen to know how this works? And if I don't have to go through immigration, what happens to my bag that I checked in at the Singapore airport?
Thanks for the help!

Are you traveling on the same airline?

You would have to check with your airline (give them a call or check their website) because some airlines will check your bags through and others will not. Depends on the arrangements between the two airlines. If you let us know which two airlines someone may be able to tell you off the top of their head.

My recent observations have been that as an arriving international passenger you WOULD go through immigration with your luggage. Then, typically just outside the exit from immigration the connecting airlines have a desk set up to re-check luggage. After going through immigration you would simply walk over to your next airline's desk. I hope this info is correct in your case, but I do agree with advice above to contact your next airline to be sure.

Which airlines, have you booked it as Singapore-Paris and Paris-Ukraine as separate tickets or Singapore-Ukraine via Paris.

If the former then the odds are you will have to pass through immigration, collect luggage, pass through customs, then check-in, blah blah blah

If the latter then you just follow the signs to whatever CDG uses for Flight Connections and don't worry about your luggage as it will be checked through

But naming which airlines would be of help