A catheter insertion device for inserting a catheter into a body of a patient includes a retractable needle for establishing access to a subcutaneous vessel of the patient and a manually extensible guidewire for guiding the initially attached catheter into the vessel. In one embodiment, the catheter insertion device includes a housing, a hollow needle retractably extending from the housing, a catheter initially disposed on a portion of the needle, a guidewire including a portion initially disposed within the needle, a guidewire advancement feature configured to selectively advance a distal end of the guidewire distally past a distal end of the needle, and a needle retention component configured to selectively enable retraction of the needle into the housing. The needle retention component is configured to be actuated by the guidewire advancement feature. In one embodiment, one-handed operation of the device is possible.