Ryan Fogle was seen on Russian television going through passport control and security at Sheremetyevo International Airport.
He also was pictured in the company of embassy staff as he wheeled a suitcase into the Moscow airport, which is used by Delta Air Lines for its direct flights to New York.
Russian security services announced on Tuesday that Fogle, a 29-year-old third secretary in the US Embassy, had been caught trying to recruit a Russian counter-terrorism officer.
Fogle, who was accused of working for America's Central Intelligence Agency (CIA), was widely shown on Russian television wearing a blond wig.
The US Embassy on Sunday again refused to comment on the case.
The attention given to the Fogle case in Russia contrasts with recent moves by Washington and Moscow to develop closer cooperation on counter-terrorism in the wake of the Boston Marathon bombing on 15 April.
Little is known publicly about Fogle's duties and activities in Russia.
The US State Department confirmed that Fogle worked as an embassy employee, but would give no details about his job.
The CIA declined comments too.