According to Official Guinness Records,
The largest notebook is 0.99 m² (10.74 ft²), achieved by Nuco International Ltd. (UK), as measured at the Business Design Center in Islington, London, UK, on 26 April 2016.It took 4 men 5 hours to bind the book and it weighs almost 40kg! The notebook was displayed at the London Stationery Show in Islington.
For a complete list of 2016 records, please visit 2016 Guinness Records in United Kingdom.