The 6ft 3in player is a strong-tackling, ball-playing 23-year-old who started his career as a trainee with West Ham United.
He went on to sign for Brenford, from whom he impressed on loan in League Two with Cheltenham Town over two spells. Onariase then joined Rotherham United before signing for Dagenham where he initially excelled on loan before signing permanently, making 63 appearances in the National League and scoring twice.
While there he earned an England C call-up and was named in the Vanarama National League team of the week three times last season.
The move is subject to league clearance.
