Poyet, who was named as Sunderland's new head coach earlier this week as Paolo Di Canio's replacement, believes he will benefit from working with De Fanti as it will allow him more time to focus on the players.
The former Brighton chief says he has no concerns over his role in the club's management structure.
"I've got no worries. When everyone is working for the same aim that is for the good of the club," insisted Poyet.
"I need Roberto and I need Roberto to do well for me because the better Roberto does, the better players I get."
Poyet admits he will have some say in who the club will try to sign in the transfer market, but is happy to put his trust in De Fanti's judgement.
"I think it's a relationship," added Poyet. "You have to explain to him exactly what you want and for him to look for the players.
"I cannot do this job. I mean, the big ones I see every weekend but to find other players - well, someone needs to do it. This is our recruitment system.
"We will sit down, discuss the qualities of the players and then the club needs to make the decision on the financials. Then you are coming to the conclusion [on targets].
"I think that's fair and I'm happy with it. I've got no issues with it whatsoever."