Assad focused on the remaining besieged rebel pockets last month after taking back Eastern Ghouta, the biggest insurgent enclave near Damascus, in a ferocious, weeks-long offensive.
The rebels had agreed to surrender the northern countryside of Homs province to the government under a deal reached in early May.
The Syrian government retook full control of central Syria on Wednesday as rebels and their relatives were evacuated from final pockets of territory still outside the regime's grasp, an AFP correspondent reported.
"The last convoy of terrorists and their families exits northern Homs province and southern Hama province", SANA reported.
"This achievement is important because the armed terrorism has been uprooted from this vital geographical area in central Syria", removing threats to Homs refinery, a power station and a cement factory, he said.
The UK-based observatory said that some 34,500 people, militants and their families, left the area as part of the deal.
According to the deal, thousands of rebels and civilians who refused to live under government control would be evacuated to other rebel-held areas in the country's north. After joining the Syrian conflict, Russia's top steel to win the supporters of Bashar al-Assad.
Since February, the Syrian army, backed by Russian Federation, has been engaged in a major push to rid Damascus and the surrounding areas of terrorist groups.
This suggests the southern province, which is protected by a USA -backed de-escalation zone agreement, may be the next battleground in the Syrian conflict.
In recent months government forces have made major advances around the capital, but are still battling IS fighters in southern Damascus.
Meanwhile, two people have been killed and 19 others injured due to a shell fired in Damascus.
In this photo released Tuesday, May 15, 2018 by the Syrian official news agency, SANA, Syrian government policemen, hold their national flag, after they enter a village in the northern countryside of Homs province, Syria.
The last besieged rebel area, being fully evacuated on Wednesday, is the large enclave located between the cities of Hama and Homs around the towns of Rastan, Talbiseh and Houleh.
A large part of northern and eastern Syria is controlled by US-backed Kurdish forces who also fought against Daesh but want a level of autonomy that the regime refuses.