Bolstered by air strikes and ground troops from their ally Moscow, Syrian forces battled through the desert for weeks to reach Palmyra.
The oasis city has traded hands several times during Syria's six-year civil war and become a symbol of IS's wanton destruction of priceless cultural heritage in areas under its control.
Russian Defence Minister Sergei Shoigu informed President Vladimir Putin of Palmyra's recapture, a Kremlin spokesman told news agencies in Moscow.
"The Syrian army is still clearing neighbourhoods of mines and has not spread out into the whole city yet," said its director, Rami Abdel Rahman.
An army statement carried on state news agency SANA said its forces had "regained control over Palmyra and surrounding territory after a series of successful military operations".
IS has suffered a string of setbacks since taking over swathes of territory in Iraq and Syria in 2014, and its two main strongholds of Mosul and Raqa both face assaults by forces backed by a US-led coalition.
They were driven out in March 2016 but recaptured the city in December when the government was focused on seizing rebel-held east Aleppo.
Before IS first entered the city, Palmyra boasted temples, colonnaded alleys and elaborately decorated tombs that were among the best preserved classical monuments in the Middle East.
But many of the structures have been destroyed and much of the heritage looted for sale on the black market.
Moscow's support has been key in the Syrian army's Palmyra push, and its warplanes continued to bombard IS positions inside and near the city today, the Observatory reported.
After losing ground in the early years of the war, Assad's regime has regained significant territory - including by pushing rebel forces out of second city Aleppo last year - thanks in large part to Russian support.
Disclaimer: No Business Standard Journalist was involved in creation of this content
You’ve reached your limit of {{free_limit}} free articles this month.
Subscribe now for unlimited access.
Already subscribed? Log in
Subscribe to read the full story →
Smart Quarterly
₹900
3 Months
₹300/Month
Smart Essential
₹2,700
1 Year
₹225/Month
Super Saver
₹3,900
2 Years
₹162/Month
Renews automatically, cancel anytime
Here’s what’s included in our digital subscription plans
Access to Exclusive Premium Stories
Over 30 subscriber-only stories daily, handpicked by our editors


Complimentary Access to The New York Times
News, Games, Cooking, Audio, Wirecutter & The Athletic
Business Standard Epaper
Digital replica of our daily newspaper — with options to read, save, and share


Curated Newsletters
Insights on markets, finance, politics, tech, and more delivered to your inbox
Market Analysis & Investment Insights
In-depth market analysis & insights with access to The Smart Investor


Archives
Repository of articles and publications dating back to 1997
Ad-free Reading
Uninterrupted reading experience with no advertisements


Seamless Access Across All Devices
Access Business Standard across devices — mobile, tablet, or PC, via web or app