The former Cheltenham midfielder put pen to paper on a two and a half year deal after the Iron had an improved offer accepted earlier today.
Nigel Adkins had an offer of £100,000 rejected earlier in the transfer window but an improved offer has lured McCann to Glanford Park. Barnsley were insistent on a fee of around £400,000.
The six figure sum agreed between the two sides will remain undisclosed.