Highly-rated young Everton player Bowler has signed on a season-long loan, with Tafazolli penning a two-year deal with the option of a third year after impressing on trial.
Bowler joined the Toffees from QPR in the summer of 2017 and played a crucial role in Everton’s Under-23s claiming a Premier League 2 and Premier League Trophy double in 2018-19.
Ahead of joining Hull, the 20-year-old signed a contract extension with Everton until June 2021.
Tafazolli, 27, was a free agent after leaving Peterborough United where he previously worked with Tigers head coach Grant McCann.
Meanwhile, Sheffield United are closing in on a club record move for Bournemouth striker Lys Mousset.
The 23-year-old Frenchman travelled up to South Yorkshire on Thursday ahead of a medical and the deal could be finalised later today.
West Brom remain firmly in the hunt to sign Rotherham United utility man Semi Ajayi, subject of two failed bids from separate Championship clubs this week.
Speculation has been rife surrounding the future of the versatile 25-year-old throughout the summer, with manager Paul Warne confirming that two recent offers have been turned down from two different clubs, speaking after his side’s friendly win at Bradford Park Avenue on Wednesday night.
Warne refused to divulge the identity of either side, but it is understood that West Brom are one of the teams.
Despite Rotherham currently holding firm regarding Ajayi, Albion are not expected to be put off by the knockback and are likely to maintain their interest in the Londoner, who did not play in the Millers’ friendly at the Horsfall Stadium.
Middlesbrough centre-half Aden Flint is poised to complete a move to Championship rivals Cardiff City today – in a deal which could be worth up to £6m.
Cardiff are to pay an initial fee of £4m for the 29-year-old, which could potentially rise to £6m.
Flint joined Boro in a £7m move from Bristol City last summer.