Background Price promotions are a promising intervention for encouraging healthier food purchasing. We sought to assess the impact of a targeted direct marketing price promotion combined with healthy eating advice and recipe suggestions on purchase of selected healthier foods by low income consumers. Methods We conducted a randomised controlled trial (n=53,367) of a direct marketing price promotion (Buywell) combined with healthy eating advice and recipe suggestions for low income consumers identified as ‘less healthy’ shoppers. Impact was assessed using electronic point of sale data for UK low income shoppers before, during and after the promotion. Results The proportion of customers buying promoted products in the intervention month increased by between 1.4% and 2.8% for four of the five products. When product switching was examined for semi-skimmed/skimmed milk, a modest increase (1%) was found in the intervention month of customers switching from full fat to low fat milk. This represented 8% of customers who previously bought only full fat milk. Effects were generally not sustained after the promotion period. Conclusions Short-term direct marketing price promotions combined with healthy eating advice and recipe suggestions targeted at low income consumers are feasible and can have a modest impact on short term food purchasing behaviour but further approaches are needed to help sustain these changes.