The Dees conceded just eight points in the second half as they powered to a 11.8. (74) to 2.11 (23) win at Casey Field on Sunday.
Elsewhere, Sydney beat GWS by 31 points and Richmond downed St Kilda by 15.
Melbourne (5-0) had too much firepower for Port in breezy conditions, outscoring Port 6.6 to 1.4 after halftime as nine of their players kicked goals.
Mia Austin kicked two In the first quarter while Tayla Harris also bagged two and tallied 15 possessions in an impressive all round performance.
Port (2-3) had won their two previous away games, but produced another inept goal kicking performance after tallying 1.8 last week.
Kicking with the breeze in the second quarter, Port scored just 0.5 but still had one more scoring shot than Melbourne before halftime, when they trailed by 13.
Olivia Purcell drove the Demons with 30 disposals and 11 tackles, while Abbey Dowrick competed well for Port, tallying 23 touches eight clearances and five tackles.
Melbourne face their fellow top three teams, Carlton and North Melbourne, in their next two games.
"We're really proud of the way we've started the season, but it means nothing unless we keep it rolling," Harris told Fox and Kayo.
Sydney (4-1) moved above Geelong into fourth and kicked their highest score of the season in a 13.9 (87) to 8.8 (56) home win over GWS (1-4).
Sydney's Chloe Molloy kicked 4.4 in front of Henson Park's largest AFLW crowd of 7,340.
The game was held up for several minutes in the final quarter when Sydney's Sophia Hurley needed to be stretchered off.
"Sophie has gone to hospital with what looks like a tough ankle injury, " Swans coach Col O'Riordan said.
At the time of the injury, Hurley was the joint leading possession getter in the game with 25.
Isabel Huntington kicked three goals for GWS, who won the final quarter, but were made to pay for some poor defence earlier in the game.
Richmond (3-2) produced a strong finish to beat winless St Kilda 9.4 (58) to 6.7 (43)
Emelia Yassir, Gabby Seymour and Katie Brennan all kicked two goals for Richmond, who led for most of the game.
Saints kicked their highest score of the season and it was their smallest losing margin of the campaign.
Jade McLay, in just her third AFLW game, was a standout for the Saints (0-5).
The 19-year-old midfielder was terrific when moved forward, kicking four goals, three In the second quarter, to briefly put Saints in front.
Richmond wrested back the lead with three straight goals to lead at halftime and stayed ahead for the rest of the game.
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