If an individual is still working and on an employer plan, yes you can.
If, however, you are not working, you will incur a penalty of 10% for each year you did not sign up for Part B.
If you did not enroll in Part B when you were first eligible, now is the time to contact Social Security. Individuals who did not enroll onto Part B when first eligible can contact Social Security during January thru March to request enrollment onto Part B; however, your Part B will not be effective until July 1st.
With your July 1st effective date for Part B, you will be given a special election period to select either a Medicare supplement and stand-alone drug plan /or/ a Medicare Advantage plan to fill in the gaps not covered by Medicare alone.