The 20-year-old becomes Saddlers boss Darrell Clarke’s fifth summer signing, following the arrivals of Stuart Sinclair, James Clarke, James Hardy and Elijah Adebayo.
Manchester-born Kiersey joined the Toffees’ academy aged ten and was named the Under-18s’ Player of the Season for 2016/17.
Awarded his first professional contract in May 2017, he helped Everton’s Under-23s win a league and cup double last season and also featured twice in the EFL Trophy.
Following Jack's arrival, Walsall boss Darrell Clarke spoke to club journalists and welcomed him to the club, the gaffer said; "Jack is someone I’ve monitored for a few years.
"There were good reports coming out of Everton and he just missed out on getting a contract extension.
"He had an injury 18 months ago but he’s fully recovered from that and we’re hoping to turn him into a better player.
"It’s for the lad to prove himself over a short period and we’ll look to extend his contract if he produces the goods."
Following Jack's arrival, Walsall boss Darrell Clarke spoke to club journalists and welcomed him to the club, the gaffer said; "Jack is someone I’ve monitored for a few years.
"There were good reports coming out of Everton and he just missed out on getting a contract extension.
"He had an injury 18 months ago but he’s fully recovered from that and we’re hoping to turn him into a better player.
"It’s for the lad to prove himself over a short period and we’ll look to extend his contract if he produces the goods."