First Minister Nicola Sturgeon confirmed the funding at the Turriff Show in Aberdeenshire earlier this week.
The sheep sector is currently worth £892m to Scotland.
Sturgeon said: “The food and drink sector plays an important part in Scotland’s economy, so it is important we promote our premium produce.
“The strength of our farming industry would not be possible without the dedication and commitment of the farmers who work tirelessly to produce high-quality meat.
“That hard work and premium product is recognised by the protection given by the EU to the Scotch Lamb brand and we will be working hard to continue that protection in the future.
“I’m pleased we could support this year’s campaign, which will help encourage consumers to buy Scotch Lamb as part of their regular shopping.”
Jim McLaren, Quality Meat Scotland chairman, said: “The announcement by the First Minister is fantastic news for the Scottish sheep industry and it’s a great boost for our producers.
“This additional funding will enhance our comprehensive marketing and public relations Scotch Lamb PGI campaign, which is due to launch at the end of August.
“The eight-week campaign will spread the word to Scottish consumers about the quality, taste and versatility of Scotch Lamb – the perfect mid-week meal.”
NFU Scotland vice president Martin Kennedy also welcomed the announcement.
“The announcement by the First Minister of additional funding for Scotch Lamb marketing is great news for our lamb producers. The move by the Scottish Government to further support the sector in this way is a significant marker of the positive impact that the Scottish sheep sector has on the Scottish economy.
“This news comes at an important time for sheep farmers. With ongoing Brexit uncertainty, this news will bring a confidence boost as we head in to peak lamb production. The Lairg store lamb sale taking place next week, one of the largest sheep sales in Europe, often provides a barometer for sheep farming’s fortunes, so this is the right time to be positive about our sector.”