Both players underwent medicals at the KC Stadium on Tuesday and they both came through them with flying colours.
Nottingham Forest are willing to let midfielder McKenna move as the 33-year-old was entering the final year of his contract at the City Ground.
McKenna is believed to have agreed a two-year deal at Hull and he will add much-needed experience to Pearson's side.
Hobbs has been a long-term target for Hull after enjoying a successful campaign on loan from Leicester last term.
The former Liverpool man is expected to sign a three-year deal at Hull after they agreed a fee in the region of £850,000 for his services.