He is among the founders of Al Shabaab, after the collapse of the Union of the Islamic Courts, a coalition of Islamists that controlled most of the southern and central regions of Somalia, including the capital Mogadishu, in 2006.
Estimated to be in his 50s, Robow is one of al-Shabab's most experienced leaders, having travelled to Afghanistan and trained alongside al-Qaeda around 2000 after studies in Sudan. The action against al-Shabab leaders was started by al-Shabab leader Ahmed Abdi Godane who started to kill his rivals. Godane was killed in a USA airstrike in 2014.
An army official said in June there were negotiations between the government and Robow but there were no guarantees that he would defect. The government should eliminate Robow and the militants who fight him.
Former Al-Shabaab deputy leader and spokesman Mukhtar Robow Ali surrendered to Somali authorities on Sunday, according to a state official.
Already under house arrest in Mogadishu is the former spiritual al-Shabab leader Sheikh Hassan Dahir Aweys.
Al-Shabab also faces a new military push from the USA after President Donald Trump approved expanded operations, including air strikes.
Al-Shabab previous year was named the deadliest Islamic extremist group in Africa, with more than 4,200 people killed in 2016, according to the Washington-based Africa Center for Strategic Studies.
The fighters pledged to step up attacks after the recently elected government of President Mohamed Abdullahi "Farmajo" Mohamed launched a new military offensive against it. The group also faces a new military push from the United States after President Donald Trump approved expanded operations, including airstrikes.
Earlier this week, Robow lost at least 19 of his fighters to al-Shabab, our correspondent said.