A Prince George's County jury convicted 47-year-old Darrell Lynn Bellard of Dickinson, Texas, in April on four counts of first-degree murder in the 2010 slayings.
He was sentenced on Friday to multiple life and life without parole sentences plus 80 years.
Bellard was convicted of killing Dawn Brooks, her two young children and the children's aunt, Mwasiti Sikyala.
Prosecutors say Bellard killed because he believed Brooks and Sikyala were responsible for the disappearance of approximately 60 pounds of marijuana that Bellard brought with him from Texas to sell.
One of Bellard's attorneys did not immediately return a telephone call Friday afternoon requesting comment.