The Vikings captain hit nine fours and two sixes – ending six short of his century – before Birmingham replied with 181 for five including a 46 ball 64 from Sam Hain who hit five fours and two sixes.
Birmingham won the toss but Yorkshire made a solid start and the opening 50 stand came inside six overs – off 32 balls – after some loose bowling from the Bears early on.
Lyth brought up the half century with a boundary as Vikings made the most of the powerplay.
Vikings were 92 for no wicket after 10 overs and Kohler-Cadmore reached his 50 after hitting seven fours and a six, with the pair completing a century stand a in the 12th over.
But Bears made the breakthrough when Lyth tried to pull a George Garrett ball and was caught on the boundary by Dom Sibley on the deep mid-wicket boundary.
Garrett, aged 19, earned his first wicket in T20 cricket as a result with the score on 102 – that follows his wicket on his first-class debut against Somerset this month.
But Yorkshire were still in a strong position and David Willey kit the Vikings’ momentum going as he hit the first and third ball of his innings for six.
Willey continued to take the game to Birmingham and drove Chris Green for a huge straight six.
But Bears picked up a second wicket as Willey tried one big shot too many and hit Green’s full toss to long-off where he was caught by Will Rhodes after making a rapid 25 off 10 balls to leave Vikings 137 for two.
Harry Brook came in and provided more valuable support for Kohler-Cadmore and the pair hauled in 24 runs from the 17th over.
Vikings reached 200 off the last ball of the innings leaving Kohler-Cadmore not out after carrying his bat.
Bears made an encouraging start and Ed Pollock took the game to Yorkshire only to edge Tim Bresnan to wicket keeper Tattersall and depart for 22 hitting four boundaries and a six.
But Chris Green then went from his second delivery as Brennan struck again in the same over with Will Fraine taking a fine catch as Bears were reduced to 35 for two.
And it was 56 for three when Matt Pillans bowled Lamb for 11 – but Vikings took command when Lyth trapped opener Dom Sibley for 37 with the Bears score on 100.
