Portrayed by actor Mark Indelicato, Justin is raised by his single mother Hilda, both of whom live with his aunt Betty and grandfather Ignacio.

Although the character exhibits stereotypically gay interests and flamboyant mannerisms, the show does not address his sexuality until its fourth season, despite constant speculation and support from his family.

Justin was created by series creator Silvio Horta, who partially based the character on his own upbringing as a gay teenager raised by a single mother.

Instead of immediately coming out to his family, Justin confides in Betty's openly gay co-worker Marc St. James, who helps him cope with high school bullies and dating.

[13] Although the show originally opted not to address Justin's sexual orientation, Horta – who was gay himself – decided the character should experience a gradual journey as he matures.

[13] Indelicato believes the writers initially did not quite know what to do with Justin's character, since he was originally envisioned as little more than the show's "funny, flamboyant, kind of questionable kid",[33] created mainly "to counter Betty in a humorous and touching way".

[22] Ugly Betty's parent network ABC would typically avoid providing a direct answer when asked about Justin's sexual orientation by the media.

[3] Actor Michael Urie, who plays Marc, concurred that a positive friendship between an older and younger gay man was a rare dynamic never conveyed on television prior to Ugly Betty.

[44] Another early hint occurs when Marc tells Betty "I’m sure your nephew is tired of being in the closet", after Justin spends much of the afternoon working in MODE's wardrobe department.

[22] Waymon Hudson of LGBTQ Nation described Justin as "an effeminate, musical-loving, fashion designing, tap dancing, kid" who is "secure and happy with who he is in all his fabulousity".

[45] TV Guide's Angelique Anest believes Justin's "wings [were] clipped by not growing up inside the sequined and bedazzled mansion he occupied in his head.

"[46] In a 2006 article, Gretchen Dukowitz of Advocate theorized that ABC's hesitance to confirm Justin's homosexuality "doesn’t mean he won’t eventually come out", observing that the show shares a network with the sitcom on which comedian Ellen DeGeneres came out as gay.

[47] Lyle Masaki of NewNowNext.com summarized Justin as a character who grows from "an effeminate pre-teen his family presumed would come out as gay someday, to the teen who rebels by insisting he’s straight and finally the boy who falls in love for the first time and realizes nothing matters as much.

"[14] Describing the character as "precociously smart", Urie identified Justin's family as a "beautiful example of how people across this country could deal with a situation that's maybe outside their comfort zone.

[52] In 2006, The Austin Chronicle's Belinda Acosta predicted Justin would develop a cult following due to the series' delicate treatment of his impending future as a gay man.

[28] In 2006, GLAAD originally did not include Justin in their annual tally of gay, lesbian, bisexual and transgender characters on television; GLAAD entertainment media director Damon Romine explained the character was omitted due to his unconfirmed sexuality, elaborating, "To say he’s gay based on [his personality] means viewers are letting stereotypes decide for them the definition of gender and sexuality.

"[60] Although teenage characters exploring their sexuality were becoming more common on television, the Los Angeles Times' Maria Elena Fernandez believes Justin "stands out because TV viewers have never before seen a child slowly growing into himself in quite this way.

"[3] In September 2007, Slate identified Justin as one of the characters the magazine looks forward to watching during the fall 2007 television season, calling his family's support a lovely but fantastical scenario.

[8] Maria Elena Fernandez of the Los Angeles Times reflected that, during the show's early seasons, Justin "stood out as a fresh TV character, a child too young to understand or proclaim his sexual orientation but compellingly comfortable in his own skin.

Writing for the GLAAD website, Lauren Mattia said Justin "sheds a much needed light on the struggles that gay teens face as they try to come to terms with their newly discovered identity.

"[64] Describing Justin's first kiss as well-handled, Tim Stack of Entertainment Weekly commended producers "for putting something so brave and progressive on network television.

"[14] Queerty wrote that while some critics might dismiss Justin's acceptance by his family as fantastical, they congratulated the writers for depicting "a Mexican-American fey kid coming out to his mother in front of millions of viewers" in a non-chintzy manner.

"[68][69] Reviewing "The Past Presents the Future", Stransky credits moments such as Justin's coming out with helping "Ugly Betty go down in television history.

"[70] Autostraddle television critics named Justin one of their favorite "baby gays" of all-time, believing Ugly Betty approached his storylines better than some of its successors, calling it "near perfection" and deserving of more attention.

[17] Screen Rant's Zarreen Moghbelpour ranked Justin Ugly Betty's seventh most likeable character, describing him as "an encouraging presence on the show and a person who is true to who he is.

[71] NewNowNext.com's Alexander Stevenson wrote that Justin provided "mainstream audiences" with "an effeminate and nontraditional teen who is proud and confident and whose family loves him unconditionally, delivering a beautiful message of acceptance of gay or questioning youth.

"[72] Entertainment Tonight's Manuel Betancourt believes the character has had a positive impact on an entire generation of LGBT teenagers who "found strength in Justin’s self-assurance".

[40] Elle writer Gabe Bergado believes "If you were a gay kid in the closet during the ‘00s, the love Hilda had for her son gave you the much-needed hope that everything would be all right.

[59] Gay Times named Justin one of television's 30 most iconic queer characters, with author Sam Damshenas describing him as "incredibly influential".

[75] Parade's Mary Margaret recognized Justin as one of television's most groundbreaking gay characters, commending the show for approaching his developing adolescent sexuality "humorously and tenderly.