The explosion took place near the southeast corner of the embassy compound at around 1pm local time (05:00 GMT) on Thursday, read a statement from the US embassy in Beijing.
"Other than the bomber, no other people were injured and there was no damage to embassy property," the statement said.
Beijing police said the suspect, a 26-year-old man from China's Inner Mongolia region, was taken to hospital for treatment. No information has been released by authorities regarding his motives.
Al Jazeera's Adrian Brown, reporting from Beijing, said staff inside the embassy was "evacuated" to secure parts of the building under the guidance of US marines following a "loud explosion" nearby, according to an embassy staff.
Normal services have since resumed at the embassy.
China's state-run Global Times newspaper reported, citing a witness, that police took away a woman who sprayed herself with petrol in a suspected self-immolation attempt outside the embassy around two hours prior to the blast.
Authorities are yet to comment on the report.