Last weekend the Athlone-born teenager started against French powerhouses Biarritz in round 3 of the Heineken Cup and contributed significantly to the 22-14 victory over the defending Amlin Challenge Cup champions.
Henshaw was named on the bench for the RaboDirect PRO12 opener against the Cardiff Blues back in September. He took his chance well and was called up for the subsequent two games.
He then played the full 80 minutes against Glasgow Warriors and Leinster, first at centre before moving to full-back.
Since then, he has established himself as a key component in Connacht's back-line and is one of only two squad members to have featured in all 13 games this season.
Henshaw has represented Ireland at Under-19 level and wasalso part of the 2011 Ireland Schools team who were crowned FIRA-AER European Under-18 champions following their 17-8 final win over England.
He has also played for the Westmeath minor footballers and represented his county in 2010 and 2011. He balances his rugby with his academic studies at NUIG where he is a first year Arts student and faces exams later this month.
Robbie put pen to paper on his contract this week and commented: "I'm absolutely delighted to have signed a full contract with Connacht. This is my home province and it's so good to have the chance to play here.
"Last year, my ambitions were to get into the Academy, that's all I wanted. Then I got on the bench for the first game of the season and the last three months have been amazing.
"Nigel (Carolan) has been great to me and Eric (Elwood) has given young players a chance here, so I owe them both a lot.
"Connacht has progressed so much in recent years and a few years ago it wouldn't have been possible for me to be playing for my local region."
Commenting on the latest contract extension, Connacht CEO Tom Sears said: "Robbie is another one of the outstanding young talents we have at Connacht and we are delighted he signed a new contract, one he fully deserves."