The 21-year-old, who can play in defence and midfield, was named in Safet Susic's 23-man squad for the marquee tournament that starts in Brazil on Thursday.
Bosnia-Herzegovina are appearing in the World Cup for the first time since becoming an independent nation.
And Besic is relishing the challenge, and feels the team are in good stead ahead of Sunday's Group F opener against Argentina, particularly after beating Ivory Coast and Mexico in warm-up friendlies.
"(We did) a very good job (preparing) in Sarajevo, America and now here in Brazil too," he told the official website of the Football Federation of Bosnia-Herzegovina.
"It is the greatest pride of my life so far that I can represent my country at the world championships.
"(The spirit) within the team is high, the preparation matches only further increased our self-confidence and we look forward to the opener against Argentina."
As well as Argentina, Bosnia-Herzegovina meet Nigeria and Iran in the group stages.
'Obviously Messi is the best player in history and being compared to him means that you're doing things right, but I try to be myself': Barcelona star responds to comparisons with Argentine legend
'Darwin Nunez would be gold for Arsenal': Liverpool legend claims Gunners should have signed Uruguayan striker in January
