Russell, who is second overall and level on points with Hamilton in the championship but ahead 2-1 on wins, lapped with a best time of one minute 22.219 seconds at the fastest track on the calendar and one of the most historic.
Seven-time world champion Hamilton, who is going for a record sixth Italian Grand Prix win at Monza, was 0.226 slower at the "Temple of Speed", a slipstreaming track where drivers seek an aerodynamic tow from others to go faster.
Russell's teammate Kimi Antonelli, the first Italian in 73 years to be leading the championship at the Monza race, was fourth fastest with Red Bull's 2025 winner Max Verstappen third.
Antonelli, 59 points ahead of Russell and Hamilton, is set to start from the back of the grid due to engine penalties -- giving his rivals a great chance to cut the gap to the top.
Russell was also fastest on Friday after a Ferrari one-two in the opening session.
Lando Norris, McLaren's reigning world champion and winner of the last two races, was fifth, 0.406 off the pace, with Ferrari's Charles Leclerc sixth.
Racing Bulls' Arvid Lindblad was seventh followed by McLaren's Oscar Piastri with Alpine's Pierre Gasly and Franco Colapinto completing the top 10.
Hamilton and Verstappen almost collided in a late clash, after Hamilton passed the Red Bull at Parabolica before the Ferrari ultimately ran wide, with the stewards taking note.
"He caused that," said Verstappen over the radio. "I got blocked by Max," said Hamilton.
The top 12 were all within a second of Russell's time.