In the absence of the injured Marc-Andre ter Stegen, Inaki Pena was forced into early action in his first start of the season, diving down low to thwart Carles Perez.
Getafe were ultimately made to rue that missed opportunity a Lewandowski put Barcelona in front in the 19th minute, tucking the ball home after David Soria pushed Jules Kounde's cross back into the danger zone.
The strike represented Lewandowski's 49th goal in the Spanish top flight, moving him past his compatriot Jan Urban for the most goals scored by a Polish player in La Liga.
Lewandowski then threatened to add to his and Barcelona's tally before the break, seeing a goal ruled out for offside before he drew a near-post save from Soria.
The Blaugrana continued to create chances in the second period, with Raphinha and Lamine Yamal forcing Soria into action before the latter skimmed the Getafe crossbar.
Eric Garcia then lifted the ball over the crossbar from close range, ensuring that Getafe went into the closing stages with hopes of salvaging a point from the contest.
Getafe created the chance that they had been waiting for in stoppage time when a low cross picked out Borja Mayoral in the centre of the box, but the former Real Madrid forward was unable to make a meaningful connection.
As a result of that missed opportunity, Getafe slumped to their third defeat of the season as Barcelona celebrated their seventh successive league victory of the campaign.
Barcelona move four points clear of Real Madrid, while Getafe are languishing in the drop zone after failing to win any of their opening seven matches.
BARCELONA VS. GETAFE HIGHLIGHTS
Lewandowski goal vs. Getafe (19th min, Barcelona 1-0 Getafe)
Soria will be frustrated with that. The Getafe goalkeeper can only push Kounde's lofted cross into the path of Lewandowski. The Poland international has the simple task of guiding home his first goal against Getafe.
MAN OF THE MATCH - ROBERT LEWANDOWSKI
Lewandowski may have been frustrated to finish with just one goal to his name after he had an effort ruled out and saw another strike kept out by Soria.
However, he ultimately produced the game's decisive moment, showcasing his goalscoring instincts to pounce on Soria's parry and slot home his third goal in two matches.
The Poland international ultimately enjoyed another successful outing under his former Bayern Munich boss Hansi Flick and is now sitting top of the scoring charts with seven goals to his name in La Liga this season.
BARCELONA VS. GETAFE MATCH STATS
Possession: Barcelona 78%-22% Getafe
Shots: Barcelona 15-7 Getafe
Shots on target: Barcelona 4-1 Getafe
Corners: Barcelona 7-5 Getafe
Fouls: Barcelona 4-15 Getafe
BEST STATS
WHAT NEXT?
After claiming their seventh consecutive win of the league season, Barcelona will look to maintain their perfect record when they travel to El Sadar for Saturday's meeting with Osasuna.
As for the visitors, they will attempt to claim their first La Liga win since April in Saturday's home clash against Alaves.