The agency will work on promotional work, direct marketing, on-pack and partnership activity across both brands, and will aim to increase awareness as well as driving sales of the products.
It will also be responsible for increasing the brand's presence in stores.
In January, Haygarth was appointed to the £3 million direct marketing account for the PDA brand Palm.
The agency also handles FMCG brand accounts including Dairy Crest and Gillette.
Matt Brown, the head of marketing for cooking sauces at Premier Foods, said: "Loyd Grossman and Sharwood's are both outstanding brands with ambitious potential for 2009. We have challenged the Haygarth team to help drive and support our commercial objectives."