The win kept Bayern five points clear at the top as they again inflicted on their opponents their heaviest league defeat.
The Pole, who has netted 19 times in the Bundesliga this season, struck twice in the first half and slotted in his third goal in the 54th minute after Arturo Vidal had put the hosts ahead in the 17th.
Strugglers Hamburg had been confident they would not be the punch bags of past matches between the sides, having also lost 8-0 in Munich two years ago, and they had been unbeaten in their last three games.
But they looked shell-shocked as they conceded another goal by David Alaba in the 56th and substitute Kingsley Coman scored twice more within five minutes a little later.
Arjen Robben struck on the break as Hamburg again capitulated to the Bundesliga champions and current leaders.
Bayern never gave Hamburg a chance, making amends for their last-gasp 1-1 draw at Hertha Berlin last week.
They had 75 percent possession in the first half alone and could have added to their tally with Lewandowski also hitting the woodwork.
Second-placed RB Leipzig stayed five points off the pace after beating Cologne 3-1 to climb up to 48 points.
Borussia Dortmund's Aubameyang in action for Dortmund against Freiburg
Pierre-Emerick Aubameyang ended his goal drought after 471 minutes to score twice as Borussia Dortmund tightened their hold on third place with a 3-0 victory at Freiburg.
Dortmund are on 40 points, three ahead of Hoffenheim who play Schalke 04 on Sunday.
Hertha Berlin beat 10-man Eintracht Frankfurt 2-0 with goals from Vedad Ibisevic and Vladimir Darida in the second half to leapfrog their opponents into fifth place.
Eintracht, two points behind in sixth, had Haris Seferovic sent off for elbowing an opponent.
RESULTS:Hertha Berlin 2 Ibisevic 52, Darida 83
Eintracht Frankfurt 0Bayer Leverkusen 0 Mainz 2 Stefan Bell 3, Levin OEztunali 11
Bayern Munich 8 Vidal 17, Lewandowski 24(pen),42,54, Alaba 56, Coman 65,69, Robben 87
Hamburg SV 0Freiburg 0 Borussia Dortmund 3 Papastathopoulos 13, Pierre-Emerick Aubameyang 55,70
RB Leipzig 3 Forsberg 5, Maroh 34(og), Timo Werner 65
Cologne 1 Yuya Osako 53
SV Darmstadt 98 1 Marcel Heller 47
FC Augsburg 2 Paul Verhaegh 55(pen), Raul Bobadilla 85
Standings P W D L F A
Pts1
Bayern Munich 22 16 5 1 54 13
532
RB Leipzig 22 15 3 4 41 22
483
Borussia Dortmund 22 11 7 4 46 23
404
Hoffenheim 21 9 10 2 38 21
375
Hertha Berlin 22 11 4 7 30 24
376
Eintracht Frankfurt 22 10 5 7 25 22
357
Cologne 22 8 9 5 31 22
338
Bayer Leverkusen 22 9 3 10 34 32
309
Freiburg 22 9 3 10 28 39
3010
Mainz 22 8 4 10 31 37
28