Currently, people have to go via another Channel Islands customs post - either Guernsey, Jersey or Alderney - to meet immigration and customs laws.
The suggestion of a joint role has been made in a review of policing in Sark.
The island currently has two voluntary part-time officers for the 600-strong population.
Supt Nigel Taylor, from Guernsey Police, is assisting the Sark authorities with the review.
He said: "There are opportunities for a dual-warranted individual... to carry out the functions of customs and policing providing the necessary training is in place.
"[We're] exploring all the options to make sure it's cost effective policing in Sark, but it's also fit for a modern day society."
The Guernsey Border Agency and the island's police force have been united under a head of law enforcement, but no plans to merge the two organisations have been released.
Visitors to Sark may be able to travel directly to the Channel Island if the roles of police and immigration officers are combined.