The 24-year-old, who turned down the offer of a new Crewe deal, becomes Walsall's second summer signing, following the arrival of fellow 24-year-old Luke Leahy from Falkirk.
"Jon has got plenty of experience of League One from his time with Crewe," said Walsall manager Jon Whitney.
"We'll be getting Jon at a good stage of his career."
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It was taken by ex-students and staff from UWC Atlantic College in the Vale of Glamorgan who also stayed to help.
The boat will be used to try to ensure the safe landing of boats from Turkey.
A narrow stretch of water has become a crossing point for people from Syria and other countries which has claimed many lives.
College alumni Robin Jenkins and Lily Eckersley-Jones helped transfer the rescue boat to Lesbos with college tutor Michel Creber where another former student, Dr Annegret Berne, had been volunteering.
Mr Jenkins, originally from Llantwit Major and a lecturer at University of the Arts London, said: "The faces of the people on board when we come alongside is something that I cannot put in to words.
"We were a reassuring sign of safety.
"We must do more and we will start on constructing another boat."
The first vessel, named LB1 Red Mist, had formerly been used by the college at St Donat's, near Llantwit Major, and its students before being sent to Lesbos.
It is now being used by a group called the Lifeguard Hellas Training Centre.
Its design is the same as the original rigid hull inflatable boat (RIB) made in the early 1960s by students from the college and which has become the model for RNLI inshore boats across Britain - known as the Atlantic class.
Mr Jenkins set up a help group called the Atlantic Pacific Rescue Boat Project to deliver a boat to Japan to assist lifeguards and now others are being made to help rescuers in Lesbos.
He said college students working with tutor Michel Creber have already began work on a second RIB and he had also received a donation on Tuesday to cover the cost of making a third.

Cafodd yr Esgob Joanna Penberthy ei chysegru yn Esgob Tyddewi yng Nghadeirlan Llandaf am 11:00.
Roedd wedi ei hethol gan aelodau ym mis Tachwedd.
Dywedodd ei bod yn edrych ymlaen at "ymuno â phobl Tyddewi", tra bod Archesgob Cymru, Dr Barry Morgan, wedi disgrifio'r achos fel un "hanesyddol".
Daw'r penodiad yn dilyn ymddeoliad Wyn Evans, fu wrth y llyw am wyth mlynedd.
Cafodd y penderfyniad i ganiatáu menywod i fod yn esgobion ei wneud yn 2013.
Dywedodd yr Esgob Penberthy, sy'n 56 oed ac sydd wedi bod yn ficer yn Sir Gâr ac yn Ganon Tyddewi, ei bod "yn edrych ymlaen yn fawr iawn at ymuno â phobl esgobaeth Tyddewi wrth i ni fyw a rhannu ein ffydd yng Nghrist".
Esgob Joanna Penberthy
League One club Walsall have signed Crewe Alexandra defender Jon Guthrie on a two-year contract.
[NEXT_CONCEPT]
A Welsh lifeboat has been sent to Lesbos to help people trying to ensure the safety of refugees and migrants arriving by boats on the Greek island.
[NEXT_CONCEPT]
Cafodd esgob benywaidd cyntaf yr Eglwys yng Nghymru ei chysegru mewn seremoni yng Nghaerdydd ddydd Sadwrn.