Marvel Studios CONFIRMS Marvel TV is Canon

Brad Winderbaum (The head of television at Marvel Studios) confirms Netflix series are considered part of the main MCU and the Scared Timeline.

"Now that some time has passed and we can see how well integrated the stories are, I think that I, personally, Brad Winderbaum, can confidently say that they are part of the sacred timeline." "

The producer also explains why we've never had a clear answer:

"Up to this point, we've been somewhat closed off about what is or isn't our timeline." Frankly, that was born from a period in the studio where we were like 'We Must Succeed With Avengers' and another part of the company was developing the Netflix thing. We knew what they were doing, they knew what we were doing. But it was a lot, it was a lot to balance. " SOURCE : Screen Rant