Frans Carlgren received the Grand Cross of the Order of Prince Henry, a distinguished Portuguese order of knighthood. This honor was established in 1960 to mark the 500th anniversary of Prince Henry the Navigator's death, a pivotal figure in the Age of Discovery. The Order recognizes significant contributions to Portugal, the advancement of Portuguese culture, its history, and its values, with a special emphasis on maritime heritage.

The Order is structured into five tiers, and its constitution places limits on the number of recipients in each rank. The highest award, the Grand Cross, is the second-highest grade overall and is typically reserved for individuals other than heads of state. The granting of these titles is formalized by special decree from the Grand Master, who is ex officio the President of Portugal. The source material indicates that Frans Carlgren was among the Portuguese citizens and institutions awarded this significant honor.