[7] Formerly under the stage name Gemini, Castle began his hip hop career through Lupe Fiasco's Atlantic Records imprint, 1st and 15th Entertainment, where he was set to release his debut album, Troubles of the World, in early 2009.

[10] As a student in Bowen High School's visual and performing and arts program, Castle excelled and learned to develop his outstanding musical talents.

The mixtape, titled Untamed Beast, featured Lupe Fiasco only once and primarily focused on Castle as he demonstrated his singing and rapping abilities.

[10][15] In 2008, in advance of his debut album, Troubles of the World, Castle released the sixth part of the Fahrenheit 1st and 15th mixtape series, The Testimony of GemStones.

[6][7][20] As Castle began to spread rumors of his return to hip hop, he expressed his desire to leave 1st and 15th Entertainment shortly before Lupe Fiasco discontinued the label in November 2009.

[22][23] In 2013, Castle signed to Christian record label Xist Music where he later released his debut album, Blind Elephant, on May 5, 2015, after it had been delayed numerous times.

[8][24][25] The album was met with mixed reviews as it had garnered a moderate amount of interest yet left some fans disappointed by the long delays and heavily religious lyrical content.

[9] While under Xist Music, Castle has collaborated with a number of Christian hip hop artists including rap group Hostyle Gospel where he was featured on the track "Clap", which debuted on June 8, 2016.