Ungar began his career at the wedding of his sister, at the request of his grandfather, after which he continued to perform at weddings in
Williamsburg. He was originally part of Zemiros Choir, after which he switched to
Shira Choir, but eventually left the group to progress his career as a solo artist. In 2016, he released his debut album,
Shmueli 2. The album was produced by Naftali Schnitzler and features compositions by Moshe Laufer, Pinky Weber, Naftali Schnitzler and Yitzy Waldner, and arrangements by Moshe Laufer and Yoeli Dickman. In August 2017, he released the song "Mach A Bracha" as a single in anticipation for his album of the same name. He also released a music video for the song, which as of February 2026, has more than 11 million views on
YouTube. In 2018, he released the album
Mach a Bracha. The album was produced by Naftali Schnitzler and features compositions by Pinky Weber,
Beri Weber, Naftali Schnitzler and Hershy Weinberger. In 2019, he released an album called
On Stage, produced by Naftali Schnitzler, with the Hamenagnim Orchestra and Moishe Roth. The album includes over 50 wedding songs and encompasses almost an entire wedding. Ungar then released his third album, Madreigos, which, like his first two albums, was produced by Naftali Schnitzler, this time under his House of Music Label. Most of the album's compositions were by Hershy Weinberger, although other well-known composers, such as Schnitzler and Pinky Weber, composed for the album. Following the success of his
On Stage album, he released a second album in the series in 2022 called
Back Stage. The album includes 50 tracks. The album was produced by Naftali Schnitzler together with composer Hershy Weinberger, with musical arrangement by Shea Kaller. In February 2024, he released his fourth album titled
Shulem Aleichem which he produced himself and which was later voted Album of the Year 2024 by streaming app
24Six. He also released a music video for the song "
Fire" which is the second song on the album. The music video has more than 640,000 views, as of February 2026 In December 2024, he released an album of popular
Hanukkah songs, titled ''L'chaim Shmueli'', with producer Yosef Moshe Kahana. The album features arrangements by Moshe Laufer and Yehuda Galili. He also hosts a
Yiddish-language podcast titled ShmueliCast, in which he hosts various Hasidic guests. Its YouTube channel has over 10,000 subscribers. == Personal life ==