Adolescents’ dyadic relationships are likely influenced by the cultural context within which they exist. This study applied a person-oriented approach to examine how perceived support and negativity were manifested across youths’ relationships with mothers, fathers, and best friends, simultaneously, and how distinct relationship profiles were linked to adaptive and maladaptive functioning (aggression, anxious-withdrawal, prosociality) within and across cultures. Participants resided in metropolitan areas of South Korea, the United States, and Portugal (10–14 years; N = 1,233). Latent profile analyses identified relationship profiles that were culturally common or specific. Additional findings highlighted commonality in the relations between a high-quality relationship profile and adaptive functioning, as well as cultural specificity in the buffering and differential effects of distinct relationship profiles on social-behavioral outcomes.