Having celebrated his 21st birthday just six weeks ago, he has already played 12 times for the Ospreys, scoring two tries.
"It's really pleasing to have Daf commit to us, and vice versa, for us to be able to secure another talented youngster from the region" said Head Coach, Steve Tandy.
"He was identified as a player with potential within our age-grade system but has had an up and down few years. He won a senior international cap very young but we recognised that he needed a bit more nurturing and have held him back a bit accordingly, while a few injuries along the way have frustrated him.
"Looking across his last four summers, he's never been able to have a sustained pre-season as it's been Wales U18s, senior national squad and two Junior World Cups. It's exciting for us this summer, the prospect of getting some good work in with him over the coming months to really give him a chance to stake a claim for game time at the start of next season.
"He had a couple of opportunities this season and certainly grasped them, against Zebre and then Exeter in particular. Throwing him into Champions Cup action was a leap of faith and a great experience for him, tinged with the season ending injury he picked up late on.
"The pace and dynamism he brings can provide a point of difference if channeled effectively. He's got a good attitude towards learning what it takes to be effective at this level and with some sustained work over the coming months we can support him to reach his full potential, which will be great for him and for the Ospreys."
Having kicked off his rugby career at Abercrave RFC, who he helped to back to back Ospreys Cup titles as a schoolboy, Howells played regional age-grade rugby for the Ospreys before stepping up from the U18s to make his Premiership debut with Neath while still only 17, following that up with his first taste of regional rugby in two LV= Cup clashes, against the Dragons and Harlequins just weeks later.
Within months he had captained Wales at U18 level and then become one of the youngest ever senior caps after making the starting XV for the first summer test on the 2013 tour to Japan.
While he has found regional game-time limited since then he has continued to catch the eye with Wales U20 and Neath.
Speaking after signing his Ospreys contract, Howells said:
"I'm really excited and I just want to get into next season now and hopefully have a great season, injury free. If I can pick up where I left off against Exeter, that'll be a good starting point for me.
"I'm still young, I'm still learning, and I've got plenty of time ahead of me to continue developing, but I want to kick on from where I am now and really get some game time under my belt. It's not going to be easy as there are good players here in my position but that's the challenge I've got to take on over the next two seasons."
Howells is the 14th player to sign a new contract with the Ospreys since December. Captain Alun Wyn Jones, Dan Biggar and Rhys Webb, have re-signed National Dual Contracts, while Ashley Beck, Gareth Thomas, Ben John, Scott Otten, Tom Habberfield, Eli Walker, Joe Bearman and Ryan Bevington have all agreed new Ospreys deals. Meanwhile, Wales U20 Grand Slam winners, Adam Beard and Owen Watkin, have signed their first professional contracts.
In addition, the Ospreys have also confirmed the signing of Crusaders centre/wing, Kieron Fonotia on a two-year contract and he will be joined at the Liberty Stadium next season by Scarlets and Wales prop, Rhodri Jones, and Dragons hooker, Hugh Gustafson.
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