Customer Success Manager – Mid-Market & SME Growth in Portsmouth

We’re working with a fast-growing technology business operating at the intersection of digital advertising, SaaS and performance marketing. The company has built strong momentum globally and is scaling across both mid-market and SME customer segments. Their product helps advertisers improve campaign quality, drive stronger performance outcomes and make better decisions across paid acquisition channels. As the business continues to grow, they are now looking to hire a Customer Success Manager to support customer activation, retention and commercial growth across a high-volume book of business.

This is a commercially focused Customer Success role with responsibility across two core areas:

• Mid-market customer success: You will manage a portfolio of mid-market and long-tail customers across onboarding, adoption, retention and ongoing value delivery.
• SME activation and conversion: You will also work closely with smaller and self-serve customers, helping convert connected accounts into paying customers by clearly communicating value, performance impact and ROI.

This role sits firmly between customer success, growth and performance marketing. It is not a support role dressed up as CS, and it is not right for someone coming from a purely generic SaaS background with no paid media knowledge.

Key Responsibilities:

• Manage a portfolio of mid-market and long-tail customers across onboarding, activation and retention.
• Act as the main day-to-day contact for customer queries and ongoing support.
• Drive adoption and customer engagement through clear, commercially relevant communication.
• Convert SME and self-serve customers from connected accounts into paying customers.
• Build scalable outreach and activation workflows across a high-volume customer base.
• Monitor customer health, identify churn risk and take proactive action.
• Support renewals, upsell and expansion opportunities.
• Work closely with internal teams including Sales and Product to improve customer outcomes and platform usage.

Experience Required:

This role is only worth applying to if you have both of the below:

• B2B SaaS experience in a customer-facing role, such as Customer Success, Account Management or a similar post-sales/commercial function.
• Strong hands-on performance marketing experience, particularly across Google Ads and Meta.

That combination is essential. This is not the right fit for:

• Candidates with general SaaS customer success experience but no real understanding of paid media.
• Candidates from broader account management or client services backgrounds without direct exposure to performance-led digital campaigns.

Ideal Background:

• 2–5 years’ experience in Customer Success, Account Management or Performance Marketing.
• Proven experience managing customers in a B2B SaaS environment.
• Strong working knowledge of Google Ads and Meta.
• Experience managing a high-volume book of business.
• Ability to analyse performance data and turn insights into clear actions for customers.
• Strong organisation, commercial awareness and a proactive mindset.
• Experience with SME, self-serve or scaled customer models would be highly beneficial.