Software Mansion Dawid Matyjasik Nov 17, 2025

Building an Integrated React Native Brownfield App Using Expo: Step-by-Step Android Guide

Article Summary

Dawid Matyjasik from Software Mansion proves you don't need to rebuild your entire native app to adopt React Native. His integrated brownfield approach lets you modernize production apps one feature at a time, without the risk of a full rewrite.

This technical guide demonstrates how to integrate React Native into existing Android apps using Expo's brownfield capabilities. Software Mansion, a React Native core contributor, walks through building seamless two-way navigation between native Activities and React Native screens using an integrated architecture approach.

Key Takeaways

Critical Insight

The integrated brownfield approach creates a unified development environment where native Android and React Native coexist seamlessly, enabling gradual adoption without disrupting existing users or infrastructure.

The guide includes a working GitHub repo with commit-by-commit history, but there's one critical limitation around prebuild commands that could wipe your custom code.

About This Article

Problem

Large native apps with millions of active users face a tough choice. A complete React Native rewrite means pausing development, which risks feature stagnation, doubling maintenance work, and introducing regressions when the new version launches.

Solution

Dawid Matyjasik built a brownfield approach that sidesteps a full rewrite. Custom Kotlin native modules and Intent-based navigation let the app switch seamlessly between native Activities and React Native screens without rebuilding everything.

Impact

The demo moves between native and React Native layers with no noticeable delays or reloads. This proves that hybrid apps can work in production while keeping existing user bases stable.