The TV-led work will focus on the bakery chain's customer service and health credentials, including its recently launched Greggs Healthier Options range.
Due to break in January, the TV ads will be supported by outdoor, press, online and experiential activity.
The work will be focused on the UK market, where Greggs operates more than 1000 outlets, but could be rolled out to the Continent, where it is expanding.
Propaganda, which has also been briefed to handle an internal communications drive, was awarded the work following a five-way pitch.
The account moves from ad agency RPM3, which had handled the business since 2002 and had re-pitched for the work.