In February 2007, while participating as guest Cantor in a post-Tu Bishvat concert at Young Israel Beth El of Borough Park, Lemmer was recorded performing “Misratze B'rachmim.” This video was uploaded to . Soon after, Lemmer was invited to sing at the Jewish Culture Festival in Budapest, Hungary, where he sang with the as well as cantor Benzion Miller. Lemmer himself described YouTube as "the springboard" to his career.
The Boston Jewish Music Festival holds concerts, lectures, and other educational events to promote Jewish culture. On March 12, 2011, the Boston Jewish Music Festival featured a concert, "Divine Sparks – Music to Ignite Your Soul: A Concert of Kavanah," in which Lemmer performed. Bill Marx, editor of The Arts Fuse, a Boston-based online art magazine, wrote: "All of the judges found the concert ambitious and fascinating, a valuable step in expanding the creative and cultural boundaries of "Jewish music." The cantors were generally admired, with the recognition that they sang with great devotion, spiritual power, and a proud exuberance."
Every year in Washington D.C., the National Menorah is lit on the first night of Hanukkah. On December 20, 2011, Lemmer joined cantors Yaakov Motzen and Jeffrey Nadel to sing traditional Hanukkah songs with the United States Marine Band. Lemmer has since returned to Washington, D.C. in 2012, 2015, 2016, and 2017 to perform at the same event.
On April 19, 2013, the 70th anniversary of the Warsaw Ghetto uprising, Lemmer performed with the Israeli Philharmonic Orchestra at the site of the old Warsaw Ghetto as part of a large event.
In December 2011, Lemmer debuted the song and accompanying music video, "Rainbow in the Night". The song and , written by filmmaker Cecelia Margules, a daughter of Holocaust survivors, depict a Jewish family in Poland before World War II. Margules collaborated with producer and director Danny Finkelman on the film to raise awareness about the Holocaust. The portrayed Polish family end up in the Krakow Ghetto, and finally in a concentration camp. Filmed on location in Krakow, Poland, and the Majdanek concentration camp, Margules described the film as the "first-ever music video depicting the Holocaust".
On September 1, 2008, Lemmer performed sacred Jewish music with cantors Azi Scwartz and Netanel Herstik as part of a PBS special titled, " The PBS special is often aired regionally and nationally.
Discography
"Bkoil"
Released February 19, 2018, "Bkoil" is a compilation album by Mizmor Music. Lemmer performs one of the album’s seven singles, entitled "Halben Chato'einu."
"Vimaleh Mshaloseinu"
Released January 27, 2010, is Lemmer's debut studio album and features 11 songs:
Ato Nigleiso
Lo Tachmod
Shema Yisroel
Mein Zeiden's Chulem
Misratze B'rachamim
Av Harachamim
Ma Godlu Ma'asecho
Habeit Mishomayim
Umipnei Chatoeinu
Zol Shoyn Kumen Di Geulah
Lemmer 1928 version
"Unity for Justice"
"" is a single released by Aderet Music Corporation featuring over 40 singers including Lemmer. The single was created as a charity project to collect donations for a Jewish business owner.
"Rainbow in the Night" single
The audio-only single from the "Rainbow in the Night" music video was released on January 25, 2012, produced by Sparks Production and distributed by Aderet Music Corporation.
"It Is Shabbos"
Released September 19, 2014, Lemmer's second studio album, "," features 11 songs including: