Bateman, 26, arrives at the Windsor Foodservice Stadium from St Ives Town but started his career in the academy of Aston Villa.
He has also featured for Kettering Town, Basford United and Tamworth.
Gibbens, 21, featured for the Tigers on loan last season, and has joined the club permanently.
Manager Craig Parry said: “Liam is a quality footballer that has operated at a higher level and brings in a winning mentality - he has won the division before.
“His technical ability is there for all to see, and he gives us that balance down the right-hand side.
“He is a leader. He’s experienced and can help everyone in the side with his attributes.
"Lewis is a quality defender, who has played in the football league and played many times in the conference north.
“He is a centre-half that I have admired greatly. He is a player who we made a big effort to bring back on board this year."
The club has also confirmed ten players from last season's squad will remain part of Parry's team.
Those players are:
Deegan Atherton
James Baxendale
Jack Broadhead
Cody Cromack
Sebastian Malkowski
Jake Picton
Aaron Sennett-Neilson
Connor Smythe
Aleksandrs Starcenko
Ben Tomlinson
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