Bulgarian international Radostin Kishishev has won a one-year deal, after impressing Albion boss Gus Poyet during a short pre-season trial period.
The 35-year-old was keen to return to England, after a season in his native Bulgaria with Litex Lovech, and his performances in pre-season have convinced Poyet he still has much to offer at League One level.
Poyet explained, "He may be pushing 36, but he is an excellent professional, and has kept himself in superb shape throughout his career - and that is why he still has a lot to offer.
"His quality is obvious, there is no doubt about that, but we had to be sure about his fitness - and he has proved that age is no barrier.
"That experience and quality will bring a lot to the team, and will also help our younger players in their development."
Kishishev has 88 international caps, having made his debut for Bulgaria in 1996, and featured in World Cup qualifying for South Africa.
He began his career in his homeland, played for the national team at Euro 96 and in the 1998 World Cup.
He moved to Turkey in 1998 for a year with Buraspor before a switch to England in 1999 to join then-Premiership side Charlton Athletic in a £300,000 deal.
Kishishev has played close to 250 senior games in English football - the bulk of which have been with Charlton - but he has also served Leicester City and Leeds United, where he previously linked up with Poyet.
He was released by Leicester in January 2009, and returned to Litex, where he was appointed club captain and helped the club win the Bulgarian league title.
