Kinsella has already made three appearances for The Shots, since joining on loan in early January, and has now signed a contract until the end of the season.
The 23-year-old previously played fourteen games, including making seven starts, for The Us this season, following thirteen starts in the first three months of 2016/17 before suffering a long-term ankle injury.
He spent eight years in the Arsenal academy, up to under-16 level, before joining Aston Villa in 2011.
He helped the Villa academy win the Europe-wide NextGen Series in 2013 and was then named as a substitute for the first-team’s Emirates FA Cup quarter-final against West Bromwich Albion in March 2015.
Loans at Luton Town in League Two and National League side Kidderminster Harriers followed, before he joined Colchester United in July 2016.
Kinsella is The Shots' second signing of the day, after George Fowler also made his loan move permanent upon leaving Ipswich Town.