It depends on why your permit is exempt from a Labour Market Impact Assessment (LMIA).
Under Express Entry, some LMIA-exempt jobs count towards job offer points. For example, if you are working in Canada on a LMIA-exempt work permit that was issued under an international agreement or Federal-Provincial-Territorial agreement (or certain other cases), you don’t need your current employer to get an LMIA for your job offer to be valid.
If your work permit is LMIA-exempt for any other reason, your employer still needs to get an LMIA to improve your chances of being invited to apply. These exemptions apply to temporary workers, but not to Express Entry. A valid job offer supported by an LMIA could get you more points under the Comprehensive Ranking System.
A work permit on its own is not a job offer, even if it is an open work permit. You need a written offer. Find out more about valid job offers.
Find out more about which types of jobs don’t need an LMIA.