Advertisers will spend increase podcast ad spending, but at a lower rate than a year ago. This projection comes from the IAB’s 2025 Outlook: A Snapshot into Ad Spend, Opportunities, and Strategies for Growth. The IAB asserts that this report “provides critical insights into what’s ahead for audio advertising and podcasts.”
“The podcast ad market remains robust, with the IAB’s slower growth forecast reflecting a maturing industry where smaller percentage increases translate to larger dollar gains.” –IAB 2025 Outlook
As evident in the IAB-supplied graphic below, the percentage of ad spend change is anticipated to slow, from 12.6% in 2024 to 7.4% in the coming year.

The green highlight is burned into the graphic; look down to the Podcast itemization.
In a different category above, Digital Audio (excluding podcasts) shows the same predicted change: increased spend from 2024, but not as much as the increased spend in 2023-2024.
Meaningfully, advertisers as a whole plan to devote about 73% more money to the podcast channel than to digital audio excluding podcasts.