The 22-year-old is expected to put pen to paper on a three-year contract, with the option of a further year, as Hull step up preparations for their return to the Premier League.
Zambrano's first stint in East Yorkshire arrived clouded in uncertainty. He signed from Ecuadorian side LDU Quito in summer 2024 and made eight appearances before a CONMEBOL suspension halted his progress, with the South American governing body's 16-month ban later cut to 12 following a CAS appeal.
Once that suspension had run its course last November, Zambrano moved on to Maribor, a club under the same ownership umbrella as Hull via chairman Acun Ilicali, agreeing terms until 2029. He featured seven times in Slovenia's Prva Liga during the second half of the campaign, finding the net twice, and will now get an opportunity to press his claims with head coach Sergej Jakirovic.
Before the ban derailed his career, comparisons were being drawn between Zambrano and Chelsea's Moises Caicedo, with several clubs on the continent monitoring his development. His brief impact at Hull under then-manager Tim Walter included a goal in a 4-1 victory over Cardiff City, and that spell also brought his first senior call-up for Ecuador, though he did not feature.
Hull's hierarchy have long made no secret of their belief in Zambrano's talent, and Ilicali's dual ownership of both clubs has always made a return to the MKM Stadium a realistic scenario once his ban expired. The Tigers were previously restricted from completing a permanent deal due to financial constraints, but those obstacles appear to have been cleared as they build a squad for the top flight.
Zambrano's versatility in midfield is expected to give Jakirovic further options, with the Ecuadorian arriving with senior international pedigree and a point to prove after the disruption of the past two years.