Clinton's two-day visit to the Saudi capital is aimed at forging a consensus between the U.S. and Arab Gulf states on how to deal with Syrian President Bashar al-Assad's deadly crackdown on dissent.
Saudi state television reports showed Clinton meeting King Abdullah and several top Saudi officials.
Saudi Arabia fears the Syrian unrest could destabilize the region if it continues much longer and supports arming the country's opposition, a move the U.S. has not publicly endorsed.
According to Dubai-based political analyst Abdullah Abdulkhaleq, the issue of adding more arms to the conflict will be a major sticking point during Clinton's visit.
"There is a divide," said Abdulkhaleq. "The GCC (Gulf Cooperation Council) is ready to do everything possible to stop the killing in Syria, but we see that Washington is still a bit hesitant."
The Obama administration believes arming Syrian rebels would likely lead to civil war and also fears the weapons could fall into the hands of Islamic extremists.
U.S.-Saudi relations were strained last year over disagreements on how to handle regional uprisings. That discord has since subsided.
On Saturday, Clinton is scheduled to launch a new " strategic forum" between the United States and the
Gulf Cooperation Council, a political and economic union of Saudi Arabia, Qatar, United Arab Emirates, Kuwait, Bahrain and Oman.
The purpose of the initiative is to boost U.S.-GCC cooperation in a number of fields and comes amid rising worries over Syria's Shi'ite ally Iran.
Abdulkhaleq says it is wise for the United States to strengthen its relations with Gulf States considering the current political climate in the Middle East.
"There is a vacuum in the region and the only states that are more or less working together as a group that have the resources and have the leadership are the GCC states," said Abdulkhaleq.
After leaving Riyadh, Clinton is scheduled to travel to Istanbul to participate in a "Friends of Syria" meeting,where diplomats from Western and Arab nations hope to boost opposition to Assad.
The conference comes after Assad announced this week that he would accept a six-point peace plan put forward by U.N. -Arab League envoy Kofi Annan. Annan on Friday urged swift enactment of the plan.
Clinton said Assad's words were a positive initial step, but she remains skeptical.
"Given Assad's history of overpromising and under delivering, that commitment must now be matched by immediate actions," said Clinton. "We will judge Assad's sincerity and seriousness by what he does, not by what he says. If he is ready to bring this dark chapter in Syria's history to a close, he can prove it by immediately ordering regime forces to stop firing and begin withdrawing from populated areas."
Rights groups say fresh fighting between soldiers and rebel fighters erupted in the northern Idlib province on Friday. According to the United Nations, more than 9,000 people have been killed since unrest in Syria began over a year ago.