The Advertising Standards Authority received six complaints over whether the ad was distressing or condoned unsafe practice.
The ad, created by Leo Burnett, featured a woman with a transparent plastic bag over her head. Her eyes were closed and her mouth open.
The campaign was awarded a silver Design Lion at Cannes, which included a mocked-up front cover of Cosmopolitan featuring a woman's face being suffocated by a plastic bag.
The copy explained that the lady in the image was "brutally suffocated by her own parents in an ‘honour’ killing". It encouraged support with the hashtag #RememberShafilea.
Karma Nirvana said that it aimed to highlight a "growing area of concern in the UK and to honour the memory of women murdered by their families in the name of honour".
It added that the text gave context to the image, and that the decision to run the ad had not been taken lightly.
The charity also said that The Metro, the free daily paper, did not believe the ad was contentious.
The ASA agreed that the text in the ad made it clear the intentions of the charity clear, and said that it was "unlikely to cause unjustifiable distress".
Karma Nirvana also dismissed claims that the ad encouraged unsafe practice, and explained that the audience for The Metro is adult. The Metro added that its target audience is aged between 18 and 44.
The ASA also agreed with this point and said: "Because we understood that the Metro had a predominantly adult readership and we did not consider that the ad had particular appeal to children or presented the activity in a positive light, we concluded that the ad did not condone or encourage an unsafe practice."