Defender Tin Jedvaj, midfielders Ante Coric and Marko Rog and forward Marko Pjaca claimed their berths at the expense of Duje Caleta-Car, Alen Halilovic and Domagoj Antolic.
"Every player involved in the build-up deserved to be in the squad and I had to decide which players we needed the most," Cacic told a news conference on Tuesday.
"Coric and Rog were preferred to Halilovic and Antolic because I assessed the latter two would find it more difficult to handle being fringe players at Euro 2016.
"Also, I wanted to reward Coric and Rog for exceptional efforts in the build-up and the fine club season they've had," he added, referring to the Dinamo Zagreb pair.
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Experienced defender Vedran Corluka also made the cut despite suffering an ankle injury in training on Tuesday, which local media said requires a scan to determine the damage.
Croatia's hopes will largely rest on the form of influential midfielders Luka Modric of Real Madrid and Barcelona's Ivan Rakitic, especially Modric who shone in Real's shootout win over city rivals Atletico in Saturday's Champions League final.
Former Leicester City striker Andrej Kramaric, who last week made his January loan to Bundesliga side Hoffenheim permanent, was also included after helping his new club avoid relegation.
Croatia have been drawn in Group D alongside holders Spain, Czech Republic and Turkey.
Squad:
Goalkeepers: Danijel Subasic (Monaco), Lovre Kalinic (Hajduk Split), Ivan Vargic (Rijeka)
Defenders: Vedran Corluka (Lokomotiv Moscow), Darijo Srna (Shakhtar Donetsk), Domagoj Vida (Dynamo Kiev), Sime Vrsaljko (Sassuolo), Gordon Schildenfeld (Dinamo Zagreb), Ivan Strinic (Napoli), Tin Jedvaj (Bayer Leverkusen)
Midfielders: Luka Modric, Mateo Kovacic (both Real Madrid), Ivan Rakitic (Barcelona), Marcelo Brozovic, Ivan Perisic (both Inter Milan), Milan Badelj (Fiorentina), Marko Rog, Ante Coric (both Dinamo Zagreb)
Forwards: Mario Mandzukic (Juventus), Nikola Kalinic (Fiorentina), Marko Pjaca, Duje Cop (both Dinamo Zagreb), Andrej Kramaric (Hoffenheim)
(Writing by Zoran Milosavljevic; Editing by Ken Ferris)
