The two-time Olympic 1500m champion for Britain in 1980 and 1984, stood unopposed in the vote of the World Athletics Congress in Budapest, two days ahead of the start of the world championships in the Hungarian capital.
According to World Athletics rules, Coe will be unable to stand for a fourth mandate.
Coe, a former Conservative politician who headed the local organising committee of the 2012 London Olympics, took over the presidency of the then-International Association of Athletics Federation (IAAF) reeling from a corruption scandal involving ex-president Lamine Diack.
Coe's first two mandates saw the creation in 2017 of the Athletics Integrity Unit, an independent body overseeing anti-doping, and the reinforcement of World Athletics' stance on Russia, first suspended over institutional doping and then again in 2022 over Moscow's invasion of Ukraine.
"The first four years of my mandate was making sure the ship didn't sink. We were in a very serious position," Coe said.
The next four years, he added, were about dealing with issues such as Russia, protecting the female category and boosting one-day events.
"The next four years will focus on what is the product that will future-proof the sport for the next 30 years," he said, adding that decisions on competition would be data-based and not taken by presidential whim.
