The campaign will promote Horlicks current marketing strategy as a night time beverage for people's everyday "wind down" routine.
Horlicks will have an online presence on the Smooth Radio websites, including a dedicated microsite and display advertising.
The sponsorship will be coupled with a song request feature in the 10pm slot, where listeners will be able to go online at the Smooth Radio websites and request their two favourite songs to wind down to.
In addition, each listener will be entered into a weekly draw to win a spa day.
Henrietta Prosser, GMG Radio Solution's head of national sales and programming, said: "This is a great national brand to sit on the Smooth Radio network.
"Smooth Radio, in the evenings is all about chilling out and winding down so I have no doubt that this partnership will create a great synergy on and off air."
The deal was brokered by Mediacom and launches January 4, airing Sunday through Thursday between 8pm-12am.