In the new role Thomson will lead strategy, campaigns and the press office for the classified site after a year as PR and marketing manager at supply chain standards organisation GS1 UK.
The eBay-owned brand recently ended a four-year relationship with 3 Monkeys by taking its comms in-house.
Thomson reports to Sam Diamond, head of brand and comms at Gumtree.
Diamond pointed to Thomson's background in tech and consumer PR, and track record in leading campaigns, as key reasons behind his hire.
In addition to generating quarterly consumer campaigns and managing Gumtree’s press office, Thomson will build relationships with B2B media across the areas of motors, property and recruitment.
Previously, he worked at Bite Communications where he managed PR campaigns for Nokia, Sony Professional, AMD and Box.