"The reason I came to you is to explain what we have achieved and the agreement we reached with the transitional government in Djibouti," he told a group of local officials, elders and traders at a hotel in Jawhar.
"We need you to support that agreement, which we believe serves the interest of the nation."
The Islamic Courts currently controls Jawhar, a town 90km north of Mogadishu, the Somali capital, from which Ethiopian troops recently pulled out.
The wing of the ARS headed by Sheikh Sharif signed in October an agreement with the Ethiopian-backed transitional federal administration to restart peace efforts.
It calls for an Ethiopian troop pullback and ceasefire to start this month and the activation of joint security units to gradually take over until UN peacekeepers are deployed.
Sheikh Sharif called on all Somali factions to lay down their arms and participate in what he designated as a national unity era.
In an interview to Al Jazeera, he denied the existence of a broad opposition front to the Djibouti agreement, saying that the goal of armed resistance to remove the Ethiopian forces has been achieved.
Speaking to his supporters on Saturday, Sheikh Sharif said: "We need to fulfil our commitments and implement what we have agreed on behalf of you. So you must understand that responsibility and support us to live up to the huge task ahead."
In anticipation of his arrival, heavily armed Islamic Courts fighters had secured Jawhar and patrolled the road linking the airstrip to the town centre.
"We have tightened security and our forces are patrolling the entire region," Sheikh Yusuf Mohamed, an Islamic Courts official in charge of security, told the AFP news agency.
The crowd waved branches and banners as he drove through town and chanted slogans such "Welcome home, father of peace!"
The Islamic Courts took control of much of Somalia in 2006, triggering an intervention by neighbouring Ethiopia, which propped up the UN-backed transitional government and ousted the Islamic Courts fighters.
While the group's political leadership largely fled to Eritrea, the movement's military and youth wing, the Shebab, switched to guerrilla warfare.
The Shebab, which rejected the Djibouti deal, has relentlessly targeted Ethiopian troops, Somali government forces and African Union peacekeepers.
The fighters have of late made substantial territorial gains in the country's southern and central regions.