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Yes. Influencer marketing remains an important option in a brand’s marketing mix, but it is not automatically effective or guaranteed to outperform other channels. Meta-analyses find positive average effects on engagement and purchase intention, while campaign results vary with the creator, audience, content, product, platform and measurement period. The useful question is not simply whether influencer marketing works, but which approach fits a particular goal.
What the evidence says about influencer marketing
Two peer-reviewed meta-analyses find evidence of benefits, while measuring different bodies of work. Pan and coauthors’ review synthesized 1,531 effect sizes from 251 papers; Barari, Eisend and Jain analyzed 571 effect sizes across 71 papers and 135 experimental studies. Together, they support the view that influencer marketing can affect both non-transactional outcomes, such as attitudes and engagement, and transactional outcomes, such as purchase behavior and sales. These are averages across studies, not a promise about any particular campaign.
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The reviews also point to different mechanisms behind results. Pan and coauthors find that follower social identity strongly affects attitudes and behavioral engagement; informational and hedonic qualities of posts matter more for purchase intention; and influencer communication is especially relevant to purchase behavior. Barari and coauthors report that influencer effects on engagement and purchase intention operate indirectly through credibility and attractiveness.
Both reviews emphasize that the context matters. A creator’s relevance to the audience, the message and the product can change an outcome, as can the platform and followers’ characteristics. Follower count alone is not a dependable shortcut for predicting success.
#1 Best Overall
Choose the creator for the campaign objective
There is no universally best creator tier. In Barari and coauthors’ 2025 meta-analysis, small and medium-sized influencers were more effective at driving engagement, while larger influencers had greater impact on purchase intention. That is a finding across the studies analyzed, not a rule that every small creator will outperform every large one on engagement, or vice versa.
Start with the outcome you need, then judge whether the creator’s audience and content are a credible fit:
Rank #2
| Campaign objective | What the evidence suggests | What to assess |
|---|---|---|
| Engagement | Small and medium-sized influencers were more effective on average in Barari and coauthors’ meta-analysis. | Whether the creator’s audience and subject matter fit the people you want to reach, and whether the content gives them a reason to respond. |
| Purchase intention | Larger influencers had greater impact on average in that meta-analysis. | Whether the recommendation is credible for the product and whether the post explains or demonstrates its value. |
| Sales or purchase behavior | Pan and coauthors identify influencer communication as especially relevant to purchase behavior; the review does not establish one creator size as best for sales. | Whether the message, audience, product and path to purchase fit together, and whether sales can be measured over the relevant period. |
Use the tier findings as a starting hypothesis, not a substitute for fit. The wider evidence finds mixed results around follower count, and platform and product context complicate allocation decisions. In a 2026 survey of 2,250 consumers in the US, UK and Australia, Sprout Social reports that 17% check a creator’s follower count before deciding to engage. That survey offers a snapshot of consumer attitudes, not a test of campaign performance.
ROI depends on the time horizon and the sample
The Institute of Practitioners in Advertising (IPA) published its influencer database findings on 8 October 2025. Its wider dataset covers 220 campaigns from 144 brands, across 36 sectors and 28 markets, and more than £133 million in influencer spend. The ROI comparisons below use much narrower UK campaign samples, so the broader database size should not be mistaken for the sample behind either estimate.
| Measure | IPA finding | How to read it |
|---|---|---|
| Short-term ROI index | 99, against an all-channel average of 100; based on 59 UK campaigns. | A short-term comparison close to the database’s all-channel average—not an individual campaign forecast. |
| Short-term sales contribution | 4.5%; based on the IPA’s short-term UK campaign comparison of 59 campaigns. | A reported contribution measure, distinct from the ROI index. |
| Long-term ROI index | 151; based on 18 UK campaigns. | A stronger long-term result in a smaller sample than the short-term comparison. |
| Long-term sales contribution | 6.2%; based on 18 UK campaigns. | A long-term contribution figure, not directly interchangeable with the short-term measure. |
| Long-term multiplier | 3.35; reported by the IPA for its long-term UK results based on 18 campaigns. | A separate measure from the ROI index and sales contribution. |
The figures suggest why immediate sales should not be the only lens: the IPA’s short-term ROI index was near its all-channel average, while its long-term index was higher. The different time horizons and sample sizes matter, and the IPA also reports wide variation between campaigns. It says influencer ROI did not strongly correlate with media optimization factors such as spend levels, and points to brand–creator fit and creative quality as important considerations.
For a campaign, define the desired outcome before choosing creators, and keep engagement, purchase intention and sales distinct in reporting. Set a time horizon that fits the outcome; assess immediate and longer-term contribution separately where the measurement allows; and do not treat an industry index as a prediction for your brand. The evidence does not establish that spending more, by itself, will produce stronger influencer ROI.
Credibility and disclosure are part of the campaign
A paid endorsement can lose credibility if the audience cannot tell that a material relationship exists or if the creator makes claims they cannot honestly support. For US campaigns, the Federal Trade Commission (FTC) says a material connection that could affect how people evaluate an endorsement should be disclosed. Its Endorsement Guides were revised in June 2023 and apply across media, including social media. The FTC describes the guides as guidance; it may investigate conduct it considers unfair or deceptive under the FTC Act. Requirements can differ by jurisdiction, so brands operating outside the US should check the rules that apply there.
The FTC’s November 2019 Disclosures 101 for Social Media Influencers explains that a material connection can include payment, employment, personal or family relationships, and free or discounted products. It advises putting a disclosure with the endorsement, where people can readily notice and understand it, using clear language in the same language as the endorsement. A profile-page disclosure, a note after “more,” or a disclosure buried among hashtags or links may not be enough. A platform’s disclosure tool alone may also be insufficient under the FTC’s guidance.
- For a video endorsement, disclose within the video rather than only in its description.
- For a live stream, repeat the disclosure so viewers joining later can see it.
- Do not endorse a product based on experience the creator does not have, or make claims that are untrue.
The FTC’s 2023 update specifically addressed clear and conspicuous disclosures, platform tools, fake reviews, virtual influencers, social tags, possible liability for advertisers and endorsers, and child-directed advertising. Its current endorsement guidance is available at FTC Advertisement Endorsements; the practical social-media advice appears in Disclosures 101 for Social Media Influencers.
Independent reader supportYour contribution helps us test, update, and keep practical guides available for everyone.How to decide whether it belongs in your marketing mix
- Name the outcome. Decide whether the campaign is meant to build engagement, influence purchase intention, drive sales or achieve another defined result.
- Match creator and audience. Assess whether the creator is relevant to the intended audience and product. Do not use follower count as the sole selection criterion.
- Plan the content. Give attention to the message’s informational or entertainment value, creative execution and fit with the creator’s usual communication.
- Set the measurement window. Specify what counts as short-term and longer-term impact for this campaign, and report those periods separately.
- Protect trust. Make material relationships easy to recognize and ensure the endorsement reflects the creator’s real experience and truthful claims.
Influencer marketing is worth considering when the brand can make those choices deliberately. Its average effects and the IPA’s campaign results show that it can contribute to marketing outcomes, but variation between studies and campaigns makes a well-matched, credibly executed campaign more meaningful than the label “influencer marketing” alone.
Quick Recap
Sources
- Pan and coauthors, “Influencer marketing effectiveness: A meta-analytic review”, Journal of the Academy of Marketing Science, published online 12 October 2024; 2025 volume.
- Barari, Eisend and Jain, “A meta-analysis of the effectiveness of social media influencers: Mechanisms and moderation”, Journal of the Academy of Marketing Science, published 21 May 2025.
- Institute of Practitioners in Advertising, “First-of-its-kind IPA data details strong ROI and long-term impact of Influencer Marketing”, 8 October 2025.
- Sprout Social, “The Next Wave of Influence: The 2026 Influencer Marketing Report.”
- Federal Trade Commission, “Federal Trade Commission Announces Updated Advertising Guides to Combat Deceptive Reviews and Endorsements”, June 2023.
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