Bolton goalkeeper Jussi Jaaskelainen has agreed to move to Premier League newcomers West Ham, it was announced Wednesday.
The 37-year-old has agreed personal terms with the Hammers with an option for next year, and will move to Upton Park when his Wanderers contract expires at the end of the month.
His move to the London side sees Jaaskelainen linking up again with Allardyce, who was his boss at Bolton for eight years.
"I'm delighted to be joining West Ham United," former Finland international Jaaskelainen told the Hammers' official website.
"After spending 15 years in Bolton it's a great new challenge and I'm really looking forward to it.
"Everything has happened really quickly. When the opportunity was offered to come to West Ham I didn't think twice and I just told my agent to sort it out as quickly as possible.
"I appreciate Bolton giving me permission to speak to West Ham before my contract was up and for the efforts the chairman made in trying to get me to stay.
"I would like to thank the fans for all their support over the years and I wish the players and, in particular, (manager) Owen Coyle all the best in gaining promotion at the first attempt."
Jaaskelainen joined Bolton in 1997 from Finnish club Vaasan Palloseura, but the emergence of young Hungarian keeper Adam Bogdan limited his chances.