In the closing moments of an hour of running in the Sunshine State, Russell and Hamilton moved from the back of the pack to the front.
Hamilton held on to the top position for a few seconds before being grabbed by teammate Russell. Charles Leclerc finished third for Ferrari, one place ahead of championship leader Max Verstappen.
Formula One is back in Miami for a second time on a 3.36-mile circuit built around Hard Rock Stadium – home of the NFL side Miami Dolphins – 15 miles north of the city.
The race marks the first of three rounds to be held in the United States this year F 1American owner Liberty Media has continued to build on the sport’s rise across the Atlantic.
The first event on the Las Vegas Strip will take place in November, while the Circuit of the Americas will also feature the Grand Prix of Austin – a permanent fixture on the F1 schedule since 2012.
Despite the sport’s boom, the actual competition has faced accusations of being “predictable” and “boring” with Red Bull having won 14 of the last 15 races.
Verstappen leads Red Bull teammate Sergio Perez by six points after the opening four rounds.
But Mercedes’ encouraging start here will provide hope that Red Bull may not have their way in Florida.
Russell edged out Hamilton by 0.212 s, with Leclerc three-tenths behind. Verstappen finished the first four tenths behind Russell, while his Red Bull team-mate Perez, who comfortably won the Azerbaijan Grand Prix last weekend, was only 11th.
The session was suspended for the first nine minutes when Nico Hulkenberg crashed into the wall after losing control of his Haas coming into the third corner.
With Hulkenberg’s machine in a precarious position, red flags were deployed.
Behind the top four, Carlos Sainz finished fifth for Ferrari, Alpine’s Pierre Gasly sixth and Fernando Alonso’s Aston Martin seventh.
Lando Norris finished 16th for McLaren, 1.8 seconds behind home favorite and lone American in the field, Logan Sargent, who was raised in nearby Fort Lauderdale, finished 19th of 20 runners.
The day’s closing action gets underway at 17:30 local time (22:30 UK).