Biomedicine is one of the fastest growing areas of additive manufacturing. Especially, in the field of in vitro diagnostics (IVD), contributions of 3D printing include i) rapid prototyping and iterative IVD proof-of-concept designing ranging from materials, devices to system integration; ii) conceptual design simplification and improved practicality of IVD products; iii) shifting the IVD applications from centralized labs to point-of-care testing (POCT). In this review, the latest developments of 3D printing and its advantages in IVD applications are summarized. A series of 3D-printed objects for IVD applications, including single-function modules, multi-function devices which integrate several single-function modules for specific analytical applications such as sample pre-treatment and chemo-/bio-sensing, and all-in-one systems which integrate multi-function devices and the instrument operating them, are analyzed from the perspective of functional integration. The current and potential commercial applications of 3D-printed objects in the IVD field are highlighted. The features of 3D printing, especially rapid prototyping and low start-up, enable the easy fabrication of bespoke modules, devices and systems for a range of analytical applications, and broadens the commercial IVD prospects.