He joins the Eyrie from Aylesbury United, having scored five goals in their last dozen games of the campaign.
"Everyone at the club was impressed when we saw Ty play against us on the last day of the season,” said manager Gary Setchell speaking to www.bedfordeagles.net.
“He looks a real handful and caused us issues throughout the game. I'm sure he will fit in well alongside Connor (Tomlinson) and our other attacking players to create and score plenty of chances."
Lewthwaite, 21, was with Rotherham as a youngster where he made substitute appearances in the Championship.
After leaving Yorkshire, he signed for Hampton & Richmond Borough in the National League South. With seasons disrupted due to the pandemic, he had further spells at Beaconsfield and Walton Casuals before finishing with the Ducks. He has also represented Northern Ireland in the U19s European Championships.
Lewthwaite joins Callum Donnelly having signed PitchingIn Southern League registration forms at the Eyrie. Donnelly, who scored six goals in their promotion-winning campaign last year, is starting his sixth season at the club.
The 33-year-old midfielder originally arrived at the Eyrie in 2017/18 transferring from Hitchin Town where he made over 300 appearances. His previous clubs also include Cambridge City and Boreham Wood. Since arriving in 2017/18, he has gone on to make 135 appearances in a Bedford shirt.
Setchell added: "I'm delighted that Callum has agreed to stay for another season. He was our bite in midfield last season, and performing alongside DS (Danny Setchell), Hugh (Alban Jones) and Joe (Butterworth) gave us a real engine in the middle of the park."
Contracted players Connor Tomlinson, Hugh Alban Jones, Drew Richardson and Elliot Duffy also join the squad ready for Southern League Premier Division Central football in August.
Eagles have completed their pre-season fixture list by adding the traditional visit of National League side Wealdstone on Saturday, July 23 for a 1pm kick-off.
They have also announced that they will welcome a Luton Town XI for a friendly later this summer.
Paul Benson will bring a Hatters XI to the Eyrie on Tuesday, August 2, with the game kicking off at the slightly earlier time of 7pm.
The Hatters fixture will complete the Eagles’ pre-season campaign, before the hard work of Step 3 football kicks off on Saturday, August 6.
The full pre-season schedule so far is:
Saturday July 2, 3pm - Biggleswade FC - home.Tuesday July 5, 7:45pm - Barnet FC - home.Friday July 8, 7:45pm - Stotfold FC - away.Tuesday July 12, 7:45pm - Peterborough Sports FC - home.Saturday July 16, 3pm - Harborough Town FC - away.Tuesday July 19, 7:45pm - Hemel Hempstead Town FC - home.
Saturday, July 23, 1pm – Wealdstone – home.Saturday July 30, 3pm - AFC Dunstable - away.Tuesday August 2, 7pm - Luton Town XI - home.