The agency pitched against a number of undisclosed European agencies, including shops in Italy and Germany, for the task.
The Certina brand was first launched in 1988. Despite being sold in the UK, the brand has not been actively marketed here to date, with Swatch having previously concentrated on promoting the brand in mainland Europe.
Certina has recently been through a significant product overhaul and the brand is now returning to advertising in a bid to communicate its core values.
Swatch will now be focusing its marketing activities for Certina on the US and the UK, as well as key markets such as Germany, Italy, Switzerland and France.
Spirit will produce a campaign, running from September, which will initially run across print and outdoor, though activity is likely to be extended into TV at a later date. Media buying will be handed by Swatch in-house.
Manuel Romero, the chief executive of Certina, said: "Certina is an iconic brand with a strong loyal user group. Spirit has been tasked with reinforcing these inherent values to a new, younger audience across our key markets."
Richard Hammond, Spirit's founder and managing partner, added: "Our job is to unlock Certina's true potential, and we are delighted to have been picked to handle this task."
Spirit pitched 18 months ago for Swatch's Rado brand, but was beaten to the international task by Jung Von Matt.