Alex has served as one of the vocalists of the South Korean electropop band Clazziquai since 2001. After releasing a series of short unofficial albums online, the group released their first official album Instant Pig in May 2004. They received more recognition after recording the songs Be My Love and She Is for the official soundtrack of the hit MBC romantic comedy My Name Is Kim Sam-soon. The latter won the Best OST trophy at the 2005 Mnet KM Music Video Festival. Alex also released two solo studio albums in 2008 and 2011, namely My Vintage Romance and Just Like Me, respectively.

Alex landed his first acting role in the 2007 MBC Every1 drama Finding Love. In 2010, he acted alongside Gong Hyo-jin, Lee Seon-kyun, and Honey Lee in the MBC workplace romantic comedy Pasta. His work in the series earned him a Best New Actor nomination at the MBC Drama Awards. In 2014, he appeared in tvN’s I Need Romance 3, MBC’s Hotel King, and SBS’ She’s So Lovable. In 2018, he starred in the SBS drama I Am the Mother Too, in which he was nominated for an Excellence Award at the SBS Drama Awards.

Alex’s sister Christina Chu occasionally contributes her vocals to Clazziquai. In October 2015, Alex and Rainbow’s Hyunyoung went public with their relationship. They broke up In February 2017. In January 2018, he tied the knot with his non-celebrity girlfriend in Busan.