The Deep Atmosphere Venus Investigation of Noble gases, Chemistry, and Imaging (DAVINCI) mission was selected in June 2021 as part of the NASA Discovery Program to explore Venus through remote sensing, in-situ chemistry measurements, and near-surface imaging. This mission will investigate the evolution of Venus' atmosphere using an architecture designed to optimize science-relevant measurements within the atmosphere and on targeted flybys. Currently slated to launch in June 2029, DAVINCI's Carrier-Relay-Imaging Spacecraft (CRIS) will conduct Flybys of Venus in January and November of 2030 where it will acquire remote sensing of the upper Venus atmosphere and surface. In June 2031 during a third Flyby, the Descent Sphere (DS) containing a suite of instruments will transect the atmosphere while acquiring chemistry and environmental measurements, as well as descent imaging of a highland region. The focus of this paper is the technical mission design, concept of operations and flight system design including the DS and CRIS, with mission overview and science summarized in Garvin and others (2020, 2021). The DAVINCI concept has been in development at NASA Goddard Space Flight Center (GSFC) since 2011 with substantial hardware fabrication and test. The project is managed by NASA GSFC, which provides the DS and two key instruments, and Lockheed Martin will provide CRIS and flight operations. Other instruments and major components are provided by NASA Jet Propulsion Laboratory, Johns Hopkins Applied Physics Laboratory, Malin Space Science Systems, KinetX, and other partners. Together with other planned Venus missions, DAVINCI will usher in a new phase of Venus scientific understanding via the first in situ measurements since 1985.