"It was a very difficult battle, possibly the most difficult we have faced," a soldier who identified himself as Abu Mohammed told AFP in Yabrud's central square between puffs from a water-pipe.
Earlier, the army announced it had "returned security and stability" to the town and its surroundings.
"This new success... is an important step towards securing the border area with Lebanon, and cutting off the roads and tightening the noose around the remaining terrorist cells in Damascus province," the military added, using the regime's term for rebels.
While scores of soldiers and fighters wearing different kinds of uniforms were seen in Yabrud, not one civilian could be spotted anywhere.
Graffiti in the colours of the pro-revolt flag still adorned the heavily damaged town's walls, while fighter jets were heard overhead.
The Syrian Observatory for Human Rights, a Britain-based group relying on a network of contacts inside Syria, said Hezbollah had led the operation and that fighting was ongoing on the outskirts of the town.
Five Hezbollah fighters were killed Sunday in the area, said the group.
The Observatory and sources across the border in Lebanon, meanwhile, reported multiple air raids, including with explosive-packed barrel bombs, on the area between Yabrud and the Lebanese town of Arsal.
The NGO said at least six people were killed in raids on the area, among them two children.
Syrian state television said the army was targeting "groups of terrorists" fleeing Yabrud in the direction of Arsal.
Dozens of wounded people also streamed into Arsal, including around 20 struck in air strikes inside Lebanon and 30 brought over from Syria, a medical source in the region told AFP.
In another spillover of violence, a suicide car bombing killed four people late Sunday in a Hezbollah-held area in the eastern Bekaa Valley near the Syrian border, a Lebanese security source said.
Those killed were two Hezbollah members, including a local official, and a woman and her husband who later died from their wounds, said the source.
The attack was claimed by Liwa Ahrar al-Sunna in Baalbek, an extremist Sunni Muslim group opposed to Hezbollah's involvement in Syria's war.
The fall of Yabrud comes after months of Syrian army operations in the Qalamoun region. Late last year, the army captured a string of nearby towns before turning its sights on Yabrud.
The town was once home to some 30,000 people, including a Christian minority, and had been a rebel bastion since early in the Syrian uprising that began in March 2011.
According to Abu Akram, a Syrian army soldier in Yabrud, the military now aims to take over Flita and Rankus, two rebel positions on the road to Lebanon.
- Key strategic prize -
Yabrud is a strategic prize because of its proximity to the highway and the Lebanese border, across which rebels have smuggled fighters and weapons.
The capture of the town, and continuing army operations in the surrounding area, will sever important supply lines for the rebels as they face army advances on different fronts.
The town's seizure could also pile new pressure on Arsal, which is hosting at least 51,000 Syrian refugees, many from the Qalamoun region.
Sunni Arsal is largely sympathetic to the Sunni-led uprising, and rebel fighters are believed to have rear bases in areas around the town, which are regularly targeted by Syrian warplanes.
Arsal municipality official Ahmad Fliti told AFP the Syrian air force was staging continuous raids outside the town on Sunday.
Hezbollah's involvement in Syria has prompted bomb attacks by extremist groups against areas in Lebanon sympathetic to the movement, killing mostly civilians.
The group and Lebanese security forces have said many of the car bombs used in those attacks originated in Yabrud.
The town's fall comes a day after Syria's conflict, which has killed more than 146,000 people, entered its fourth year.
The UN refugee agency says nine million Syrians have been forced from their homes, creating the world's largest displaced population.