The 41-year-old, who retired in May 2010 after winning 61 caps for Germany, left Arsenal in 2008 after making 147 appearances in five years, but is set to sign a short-term deal to help the Gunners out.
Lehmann is expected to sign as back-up until the end of the season for Spanish goalkeeper Manuel Almunia. Both reserve 'keepers, Lukasz Fabianski and Wojciech Szczesny, are sidelined with injury.
He will undergo a fitness test in the next few days and could take his place on Arsenal's bench for Saturday's Premier League match at West Bromwich Albion.
"Arsenal currently has a goalkeepering crisis and I'd like to help out," Lehmann told German daily Bild.
"This time I'm looking forward to being in a back-up role and will look to supporting Almunia. We can still win the title. We have to show that we are strong enough. I don't feeling we've thrown the season away. I think we can do it."
Lehmann was already at Arsenal before the crisis and had been working with the club's young goalkeepers as part of a six-week placement for his coaching badges.
Arsenal are three points adrift of league leaders Manchester United, but lost the League Cup final to Birmingham and suffered exits from the Champions League and FA Cup to Barcelona and United respectively.
Lehmann was working as an analyst for German broadcaster Sky when Szcesny suffered a finger injury against Barcelona and admitted he is surprised at how things have worked out.
"I didn't dream that Arsenal would then come and get me," he said.