Niasse has not been involved in a single matchday squad for Everton under Ronald Koeman and has made just five appearances for the club overall since his £13.5m move from Lokomotiv Moscow in February.
The Senegal international will now undergo a medical with the Tigers after they agreed a loan deal with Everton until the end of the season.
Evandro is also set for a medical at the Premier League strugglers, with the former Brazil Under-20 international expected to reunite with new Hull boss Marco Silva following their time together at Estoril Praia in Portugal.
The midfielder is yet to make a league appearance for Porto this season and will also move to the KCOM Stadium on loan until the end of the current campaign.
Both players are expected to join in time for Saturday's Premier League clash with Bournemouth, easing Silva's injury concerns with 13 first-team players currently unavailable for the Tigers.