當然嘛 is an emphatic interjection meaning 'of course!' or 'naturally!' It conveys strong agreement, confidence, or gentle insistence—often with a warm, friendly, or slightly playful tone. The first two characters, 當然 (dāng rán), literally mean 'as expected' or 'naturally'; the final particle 嗎 (ma) softens and adds conversational rhythm, turning the phrase into a relaxed, colloquial affirmation—not a question marker here, despite its spelling similarity to the interrogative 'ma' (嗎).

This phrase is commonly used in spoken Mandarin during casual conversations among friends, family, or colleagues to affirm something obvious, express readiness, or gently reinforce shared understanding. It carries positive emotional weight—conveying goodwill, enthusiasm, or reassurance—and rarely appears in formal writing. Its tone is warmer and more personal than plain 當然, and it often appears at the end of a sentence or as a standalone response.