THREE MOBILE APP

Designing a modern mobile experience built on a scalable design system

Role

Senior UI designer

Platforms

iOS & Android

Team

Product, UX & engineering

Results

+21% Android, +38% iOS, +65% add-on sales

As part of Three's product design team, I helped redesign the company's flagship mobile app following a major digital brand refresh.

Working alongside UX designers, product managers and engineers, I translated the new visual language into a cohesive mobile experience that aligned with our evolving design system while making everyday customer journeys faster, clearer and easier to use.

My role

Senior UI Designer

My responsibilities included:

Designing interfaces for key customer journeys
Extending the design system for native mobile
Creating reusable components
Defining interaction and motion behaviour
Collaborating closely with UX designers and engineers
Supporting implementation through documentation
Maintaining visual consistency across the product

The challenge

The previous app had become technology-led rather than user-led.

Navigation was inconsistent, key tasks were difficult to find and the experience no longer reflected Three's evolving digital brand.

Our goal was to create an app that felt intuitive from first use while bringing the visual language of the wider design system into a native mobile experience.

Designing for clarity

Working closely with the UX team, we established a clear information hierarchy throughout the application.

Each screen was structured around:

primary tasks
supporting actions
secondary content

This allowed customers to complete common journeys quickly while still making additional features easy to discover.

By extending the existing design system into mobile, we were able to maintain consistency between web and app while creating components appropriate for native interactions.

Building reusable foundations

As new patterns emerged during the project, I documented them within the design system so they could be reused across future releases.

Documentation covered:

component usage
motion behaviour
interaction patterns
native iOS and Android considerations

This ensured the app remained consistent as it continued to evolve.

Collaboration

Throughout the project I worked closely with:

UX designers to refine customer journeys
Product Managers to prioritise features
Engineers to ensure high-quality implementation
Design system colleagues to maintain consistency across platforms

This close collaboration allowed design decisions to move efficiently from concept through to production.

Outcomes

User testing demonstrated that the redesigned app was substantially easier to use than its predecessor.

During testing, participants were able to:

complete key journeys without instruction
recover independently from errors
locate features confidently
understand billing and account management more easily

Following launch, the app also delivered measurable commercial improvements, including:

+21% Android app rating
+38% iOS app rating
+20% contract handset growth during Black Friday 2025
+25% SIM-only growth during the same period
+£100k generated from data packs during the first month
+65% increase in add-on sales

The project demonstrated how a robust design system, combined with close collaboration between design, product and engineering, could deliver a significantly improved customer experience alongside measurable business results.

Continuous optimisation

Rather than treating the design as complete after launch, we continually refined key journeys based on customer feedback, analytics and evolving business priorities. This iterative approach reduced friction, improved usability and ensured the app continued to meet both customer and commercial goals.

All images © Vodafone Three