首部作品《王國之心》於2002年3月28日在日本發售,遊戲中除了原創角色外亦包括一些迪士尼卡通角色與最終幻想的遊戲角色飾演配角和召喚人物,並以最終幻想系列的角色扮演遊戲特色配合迪士尼華麗的動畫。此作推出後隨即深受好評。遊戲邀請到日本女歌手宇多田光演唱主題曲《光》(美版和Final Mix版的主題歌為《Simple and Clean》)。本作的PS2版本全球銷達640萬套[1]。
2002年12月26日,迪士尼與史克威尔再度於PS2上推出《王國之心 FINAL MIX》,又稱《王國之心國際版》,因其是將《王國之心》遊戲中的角色配音從原先的日語改以英語發售,但保留了日文選單和字幕,可以看作是將美版逆向移植後的加強版。
^Square. Kingdom Hearts. PlayStation 2. Square Electronic Arts. 2002-11-15. Leon: The Heartless have great fear of the Keyblade. That's why they'll keep coming after you no matter what.
^Square. Kingdom Hearts. PlayStation 2. Square Electronic Arts. 2002-11-15. King Mickey's Note: Donald, Sorry to rush off without sayin' goodbye, but there's big trouble brewin'. Not sure why, but the stars have been blinkin' out, one by one. And that means disaster can't be far behind. I hate to leave you all but I've gotta go check into it. There's someone with a "key"—the key to our survival. So I need you and Goofy to find him, and stick with him. Got it? We need that key or we're doomed! So go to Traverse Town and find Leon. He'll point you in the right direction. P.S. Would ya apologize to Minnie for me? Thanks, pal.
^Square. Kingdom Hearts. PlayStation 2. Square Electronic Arts. 2002-11-15. Maleficent: You see? It's just as I told you. While you toiled away trying to find your dear friend, he quite simply replaced you with some new companions. Evidently, now he values them far more than he does you. You're better off without that wretched boy. Now, think no more of him, and come with me. I'll help you find what you're searching for...
^Square. Kingdom Hearts. PlayStation 2. Square Electronic Arts. 2002-11-15. Sora: But that's impossible. How did this happen? I'm the one who fought my way here with the Keyblade! / Riku: You were just the delivery boy. Sorry, your part's over now.
^Square. Kingdom Hearts. PlayStation 2. Square Electronic Arts. 2002-11-15. Donald Duck: Goofy, let's go. We need to remember our mission. / Goofy: Oh! Well, I know the king told us to follow the key and all. But... / Donald Duck: Sora, sorry.
^Square. Kingdom Hearts. PlayStation 2. Square Electronic Arts. 2002-11-15. Sora: What? You... You're not Riku. / ... / Sora: Tell me. Who are you? / Ansem: It is I, Ansem, the seeker of darkness.
^Square. Kingdom Hearts. PlayStation 2. Square Electronic Arts. 2002-11-15. Ansem: The Keyhole cannot be completed so long as the last princess of heart still sleeps. / Sora: The princess...? Kairi's a princess? / Ansem: Yes, and without her power, the Keyhole will remain incomplete.
^Square. Kingdom Hearts. PlayStation 2. Square Electronic Arts. 2002-11-15. Ansem: Don't you see yet? The princess's heart is responding. It has been there all along. Kairi's heart rests within you! / Sora: Kairi... Kairi's inside me?
^Square. Kingdom Hearts. PlayStation 2. Square Electronic Arts. 2002-11-15. Donald: Well, now what do we do? / Sora: We've gotta find Riku and King Mickey.