He came to prominence as the leading general under Emperor Yuan (Xiao Yi)'s campaigns against the rebel general Hou Jing and other competitors for the Liang throne, and after Emperor Yuan was defeated by Western Wei in 554 and killed around the new year 555 became the de facto regent over the remaining provinces of Liang.
He made Xiao Yuanming the Marquess of Zhenyang, a cousin of Emperor Yuan and a candidate for the throne favored by Northern Qi, emperor, but four months later, his subordinate Chen Baxian carried out a coup, killing him and deposing Xiao Yuanming.
When he was Northern Wei's governor of Yingchuan Commandery (潁川郡, roughly modern Xuchang, Henan), he, along with Wang Sengbian and his brothers, surrendered to the Liang dynasty on 1 March 508.
When Xiao Yi, then the Prince of Xiangdong, was made the governor of Jiang Province (江州, modern Jiangxi) by his father Emperor Wu in 540, Wang Sengbian served on his military staff, and in 542, when a member of Ancheng Commandery (安成, roughly modern Anfu County, Ji'an, Jiangxi), Liu Jinggong (劉敬躬) rebelled, Xiao Yi sent Wang and Cao Ziying (曹子郢) against Liu.
When Xiao Yi was made governor of Jing Province (荊州, modern central and western Hubei) in 547, Wang followed him to Jing Province and was made the governor of Jingling Commandery (竟陵, roughly modern Jingmen, Hubei).
In 548, when Hou Jing, formerly an Eastern Wei general, rebelled against Emperor Wu and quickly put the capital Jiankang under siege, Xiao Yi did not personally lead forces to aid Jiankang; rather, he sent his heir apparent Xiao Fangdeng (蕭方等) and Wang Sengbian.
When the palace fell in summer 549, allowing Hou to take Emperor Wu and his crown prince Xiao Gang hostage, and Hou subsequently forced Emperor Wu to issue an edict disbanding the provincial troops under Liu's command, Wang and Pei Zhigao (裴之高) suggested Liu to make one last stand against Hou, but Liu took no action, and the provincial forces, including Xiao Fangdeng's, largely returned to their home provinces, although Wang, along with Liu and several other generals, surrendered to Hou.
Wang stopped at Baling (巴陵, in modern Yueyang, Hunan) and fortified it against a possible Hou attack.
Wang and Chen, by Xiao Yi's orders, stopped at Xunyang (尋陽, in modern Jiujiang, Jiangxi) to wait for the rest of the troops.
Records indicate that Wang's forces were lacking in military discipline, and they pillaged the people of Jiankang, stripping them of wealth and clothes.
He requested again that Xiao Yi return to Jiankang to take the throne, but Xiao Yi again declined, effectively putting Wang in charge of the eastern empire, and Wang in turn put Chen in charge of the important city Jingkou (京口, in modern Zhenjiang, Jiangsu).
Once they did, however, Wang, not wanting to aggravate Northern Qi, did not counterattack, and further, when the provincial gentry from those lost provinces requested that he attack because they did not want to be under Northern Qi rule, he rejected their requests, although when the people of Guangling (廣陵, in modern Yangzhou, Jiangsu) claimed to be ready to rise against Northern Qi, he permitted Chen to advance to Guangling, putting it under siege.
Subsequently, Northern Qi agreed to return Guangling and Liyang (歷陽, in modern Chaohu, Anhui), and the campaign ended.
Emperor Yuan summoned Wang Sengbian to rendezvous with his cousin Xiao Xun (蕭循) the Marquess of Yifeng to attack Lu.
Wang and Xiao Xun were subsequently able to defeat Lu and put Changsha under siege, but were unable to capture it quickly.
With Emperor Yuan's brother Xiao Ji the Prince of Wuling also having claimed imperial title and attacking him from the west, Emperor Yuan pardoned Wang Lin, and Lu surrendered to Wang Lin.
Emperor Yuan ordered Wang to head to Gushu (姑孰, in modern Ma'anshan, Anhui) to defend against the attack.
In fall 554, when Western Wei launched an attack on Jiangling, Emperor Yuan summoned Wang from Jiankang.
Northern Qi's Emperor Wenxuan again wanted to create a puppet Liang regime, and he created another cousin of Emperor Yuan, Xiao Yuanming the Marquess of Zhenyang, who had been an honored captive since 547 when he was captured after failing in his mission to aid Hou's rebellion against the then Eastern Wei emperor, and sent his brother Gao Huan (高渙) the Prince of Shangdang to escort Xiao Yuanming with an army.
Wang initially resisted Northern Qi's overtures, but Gao Huan quickly defeated several generals.
Meanwhile, news came that Northern Qi was preparing an attack, and Wang Sengbian sent his secretary Jiang Gan (江旰) to Jingkou to alert Chen.