Critical Internet of Things (IoT) connectivity is an emerging concept in IoT development that enables more efficient and innovative services across a wide range of industries by reliably meeting time-critical communication needs. Mobile network operators (MNOs) are in the perfect position to enable these types of time-critical services due to their ability to leverage advanced 5G networks in a systematic and cost-effective way. This Ericsson Technology Review article explores the benefits of Critical IoT connectivity in areas such as industrial control, mobility automation, remote control and real-time media. It also provides an overview of key network technologies and architectures. It concludes with several case studies based on two deployment scenarios – wide area and local area – that illustrate how well suited 5G spectrum assets are for Critical IoT use cases.