When Xiao Ying was made the governor of Guang Province (廣州, modern Guangdong) around 540, he invited Chen to serve on his staff, and subsequently, Xiao Ying made him an acting commandery governor. In 541, the people of Giao Châu Province (in modern northern Vietnam), dissatisfied with the cruel rule of Xiao Zi (蕭諮) the Marquess of Wulin (another nephew of Emperor Wu), rebelled under the leadership of Lý Bôn. Xiao Ying sent the generals Sun Jiong (孫冏) and Lu Zixiong (盧子雄) to attack Lý Bôn, with Xiao Ying overseeing the operations. In spring 542, Xiao Ying and Xiao Zi ordered Sun and Lu to attack, despite Sun and Lu's request to delay the attack to fall 542 due to fears that hot temperature could cause illnesses. When Lý Bôn crushed their forces with heavy casualties, Xiao Zi falsely accused Sun and Lu of working in concert with Lý Bôn, and Emperor Wu ordered Sun and Lu to commit suicide. Lu Zixiong's brothers Lu Zilüe (盧子略) and Lu Zilie (盧子烈) and subordinates, the brothers Du Tianhe (杜天合) and Du Sengming (杜僧明) and Zhou Wenyu (周文育,) attacked the capital of Guang Province, wanting to kill Xiao Zi and Xiao Ying to avenge Lu Zixiong. Xiao Ying ordered Chen to engage them, and he defeated them, killing Du Tianhe and capturing Du Sengming and Zhou. Believing that Du Sengming and Zhou were both good soldiers, he released them and retained them on his staff. For this accomplishment, Emperor Wu created Chen the Viscount of Xin'an, and while he did not summon Chen to the capital Jiankang, he had an artisan draw a portrait of Chen and deliver it to him. In January 544, Lý Bôn proclaimed himself emperor and named the country Vạn Xuân, ending the Second Chinese domination of Vietnam. In winter 544, Xiao Ying died, and initially, Chen started escorting Xiao Ying's casket back to Jiankang for burial. On the way, while he was still at Dayu Mountain (大庾嶺, on the borders of modern Jiangxi and Guangdong), he was ordered to rendezvous with the new governor of Giao Châu Province, Yang Piao (楊瞟), and another nephew of Emperor Wu's, Xiao Bo (蕭勃), to attack Lý Bôn.