That is what the Americans and others were looking for, as a prelude to another planned meeting of the outside powers - including Russia and Iran - later this month to prepare for rebel-regime negotiations in early January.
But that doesn't mean it's going to be plain sailing.
Many of the groups which signed up to the closing statement embracing the vision of a democratic, pluralistic, inclusive system had earlier committed themselves to seeking Islamic rule in Syria.
They may have had a change of heart. But their opponents will be wary.
One of the most radical and powerful groups, Ahrar al-Sham, which is close to the al-Qaeda-linked al-Nusra Front, is now reported to have reversed its decision to pull out of the process.
But its position highlighted the fact that many of the fighting groups are strongly Islamist in outlook. And what about al-Nusra itself, which is opposed to Islamic State but scrambled up with the other rebel groups on the ground?
The Islamist rebel groups are backed and financed by the Saudis, Qataris and Turks. If these outsiders are fully on board the process, they may be able to strong-arm those groups into toeing the line.
But much may depend on the thorny question of President Bashar al-Assad's future.
The Riyadh meeting insisted - as do the Saudis and others - that he and his inner circle must leave power before a transitional period beginning six months into the process.
That may be a bargaining position. But if it's not met, things could swiftly unravel.
What's important about the Riyadh meeting is that it creates a framework and mechanism for a broad spectrum of the Syrian opposition and rebels to engage in settlement negotiations with the regime.