The choice between REST and GraphQL gets framed as a technology decision, but the security implications often go undiscussed in the architecture meetings where the call gets made. Both styles can be secured well. Both can be implemented disastrously. The interesting question is not which one is more secure in principle, but which trade-offs each style forces a development team to confront.
Where REST Stays Predictable
REST endpoints have a known shape. The URL describes the resource, the method describes the action, and the request body describes the data. That predictability makes REST APIs relatively straightforward to inventory, monitor and secure. Standard tooling understands REST. Web application firewalls have rules for REST. Logging libraries produce useful traces for REST. A best pen testing company has decades of accumulated practice testing REST APIs, and most engineering teams have at least some staff familiar with the patterns.
Where GraphQL Trades Flexibility For Complexity
GraphQL collapses the surface to a single endpoint that accepts arbitrarily complex queries. The flexibility is wonderful for developers and challenging for defenders. A single endpoint cannot easily be rate limited the way ten REST endpoints can. Authorisation has to be enforced per resolver rather than per route. Query complexity becomes its own attack surface. None of these issues are insurmountable, but they require deliberate handling that REST mostly enforces by default.
Expert Commentary
William Fieldhouse, Director of Aardwolf Security Ltd

The teams that succeed with GraphQL treat the resolver layer as a security boundary in its own right. They write authorisation tests for every resolver, they enforce query depth and complexity limits at the gateway, and they disable introspection in production. The teams that fail with GraphQL assume the framework will handle these concerns. It will not.
Migration Paths Matter More Than Greenfields
Most organisations live with a mix of REST and GraphQL APIs rather than choosing one exclusively. The interesting design question is rarely about new applications. It is about how to evolve existing ones. Migrating a mature REST API to GraphQL is a multi-quarter project with real risks. Adding GraphQL alongside an existing REST surface multiplies the maintenance burden. Pick the approach that fits the team capacity and review the choice every couple of years as the codebase and the team change. The teams that operate both styles in parallel often find that the lessons from one improve their handling of the other. GraphQL security thinking benefits REST work and vice versa, because the underlying authorisation challenges are the same regardless of the transport.
Choose Based On Your Team, Not The Hype
GraphQL is genuinely useful when the client needs flexible data shapes and the back end has the maturity to enforce per-resolver authorisation properly. REST is genuinely useful when the operations are simple, the audit story matters and the team prefers explicit boundaries. Either way, a focused web application pen testing should be part of the validation. The right choice is the one your team can secure consistently over time.
No technology choice secures itself. The discipline behind the choice is what determines the outcome. The choice between REST and GraphQL matters less than the discipline applied to whichever choice you make. Pick the one your team can secure consistently. API security is harder than web application security in some respects and easier in others. The teams that understand the differences and design their controls accordingly tend to produce better outcomes than the ones that simply apply web thinking to API problems.