Many years of research and development of High Voltage Monolithic Active Pixel Sensors (HVMAPS) have culminated in the final design for the Mu3e pixel sensor. MuPix10 is a fully monolithic sensor with an active pixel matrix size of $20times20,mathrm{mm}^2$ produced in the $180,mathrm{nm}$ HV-CMOS process at TSI Semiconductors. The pixel size is $80times80,mathrm{mu m}^2$. Hits are read out using a column-drain architecture and sent over up to four serial links with up to $1.6,left.mathrm{Gbit}middle/mathrm{s}right.$ each. By means of DC/DC converters and exclusive usage of on-chip biasing, MuPix10 is fully operable with a minimal set of electrical connections. This is an integral requirement by the Mu3e experiment since it enables the construction of ultra-thin pixel modules with $0.1,$% of a radiation length per layer. First results from lab characterisation and testbeam campaigns are presented.