Heartstopper is widely celebrated for its overwhelmingly positive and affirming portrayal of LGBTQ+ characters and themes. It sensitively depicts the joys and challenges of queer youth, focusing on self-discovery, supportive relationships, and the importance of acceptance, making it a validating experience for its audience.

Heartstopper features a central transsexual character, Elle Argent, whose identity is portrayed with dignity, complexity, and agency. Her character arc focuses on navigating friendships and self-discovery, with her trans identity being affirmed and respected by her peers and the narrative. The overall impact is supportive and validating, exemplified by her friends' unwavering acceptance.

In the adaptation of the Heartstopper graphic novels, the characters Elle Argent and Tara Jones, who were depicted as white in the original source material, are portrayed by Black actresses in the 2022 series.