Ha joined Star Crew Entertainment (formerly known as Ardor&Able) and debuted with Hotshot as main vocalist on October 29, 2014,[3][better source needed] with a digital single "Take a Shot".

[4][better source needed] Ha and Roh Tae-hyun represented Ardor&Able Entertainment in the boy group reality survival show, Produce 101 Season 2 which aired on Mnet from April 7 until June 16, 2017.

[7][8] He was also in the sub-group Lean on Me with Hwang Min-hyun and Yoon Ji-sung, performing the song "Forever and a Day" produced by Nell.

[9] During his time with Wanna One, Ha was invited to join several TV programs, such as the eighth episode of SBS variety show Master Key,[10] Law of the Jungle Sabah,[11] which aired from July 27 to September 21, 2018,[12] and MBC singing competition program King of Masked Singer, in which he got to the third round with his rendition of "Smile Again" by Rumble fish, "Drifting Apart" by Nell, and "Appearance" by Kim Bum-soo.

[14] On January 28, Ha unveiled his self-composed song "Don't Forget" featuring former Wanna One member Park Ji-hoon.

[15][better source needed] "Don't Forget" was released as a pre-release track from his EP My Moment, with lyrics about wishing to cherish memories with loved ones.

[28] On March 1, Ha performed the songs "Bird" and "Tell Me I Love You" at One K Concert—a three-day music and art festival—at the Yeouido Parliament House grass field, which was held to commemorate the hundredth anniversary of the March 1 Movement and aims to spread the hopes of the reunification of the Korean Peninsula and peace in Northeast Asia and the world.

[29][30] He was also appointed as a guest MC for SBS Inkigayo on March 2[31][32] and on March 13, Ha took the trophy on his first solo with the song "Bird" on Show Champion[33][unreliable source] Ha sang the Korean national anthem at the 17th KTMF 2019 (the annual K Pop Festival which was held by the Korea Daily) and also perform three songs ("Bird", "Tell Me I Love You", and "Magic Castle") in front of more than twenty thousands spectators at the Hollywood Bowl - Los Angeles.

He read a novel written by Jun Sun-ok, "Ramen is cool" (라면은멋있다) and expressed his gratitude for being able to participate in such a meaningful project.

On June 5, Ha unveiled his self-composed song "Riding" featuring Dynamic Duo Gaeko,[51] a pre-release track his second EP, BXXX, which was later released on July 8.

The EP featured the medium tempo lead single "Blue" which shows a dramatic change in the song with an explosive vocal.

"Blue" was composed by Joombas (Hyuk Shin, KYUM LYK, and JJ Evans), while Ha gave his contribution as the lyricist.

[57] Since early November, he consistently ranks 1st in the top 10 most popular entertainer in non-drama TV field, for his variety show skill in SkyDrama - 'We Play'.

[62] On April 30, it was announced that Ha would be releasing an OST for the drama The King: Eternal Monarch titled "I Fall In Love" on May 2.

[65][66] Continuing his summer activities, Ha participated in an online donation concert by MBC TV and World Vision to comfort people suffering from Coronavirus disease 2019.

[73] On November 2, it was reported that Ha had ended his contract with Star Crew Entertainment starting from October 31 and he decided not to renew it.