The Norwegian says the 19-year-old will take time to return to full fitness but is pleased he is back in the first-team fold.
The 19-year-old made his return from injury during the 2-0 win at Hamilton Academical last weekend, although he is far off returning to full fitness for the Bhoys.
Deila has said as much, although he is delighted to have Denayer back in the Celtic side in any capacity.
Indeed, the Norwegian values the youngster's importance to the side and has praised his attitude while out injured.
“Jason is an important player for us and he did a good job against Hamilton but it will, of course, take time for him to get back into top shape as he has been out for so long but it was a good start for him," he told the Celtic View.
“He has remained focused but he has been anxious to get back playing football and games so I’m happy that he’s back."
Goals from Adam Matthews (a stunning strike) and Liam Henderson gave Celtic the three points at Hamilton on Saturday afternoon, a result that closed the gap behind SPL leaders Aberdeen to just two points - with the Bhoys still having two games in hand over the Dons.
Aberdeen's 3-3 draw with Dundee helped Celtic's cause considerably, while Deila's side now face league clashes with Motherwell (at home tonight) and Ross County (away).