Horton, speaking to BBC Radio Humberside at the Tigers' training base in Bormio, says a deal is also "virtually agreed" with Bernard Mendy, with the Frenchman choosing City over Sampdoria and other interested European clubs.
Capped four times by Brazil, Geovanni played for Barcelona and Benfica before returning to Cruzeiro in Brazil. He then joined Manchester City a year ago, and scored on his debut after coming on at West Ham. He then scored the winner against rivals Manchester United in his first start for the club. His third and final goal came in his only other start, in the draw at Wigan in December. He made a total of 17 substitute appearances in the Premier League before being released at the end of his contract this summer. The 28-year-old plays in central midfield or on the wing.
Right-back Mendy will also join on a free transfer, with a three-year contract waiting to be signed. He moved to Paris Saint-Germain from SM Caen in 2000, and spent the season on loan to Bolton Wanders six years ago during Phil Brown's spell as a coach at the Reebok Stadium. The 26-year-old - who can also play in midfield - is of Senegalese origin and is capped three times by France. He is aiming to get back into the national side whilst playing for Hull City in the Premier League.
Elsewhere today, Hull City have unveiled the new home kit, which goes on sale tomorrow. The shirt is a return to black and amber stripes with black shorts and socks. The goalkeeper's shirt is light blue, with shorts and socks matching the outfield teammates.