Hastert is set to start work Monday as senior adviser to Dickstein Shapiro's government law and strategy group, The Hill reported Friday.
Hastert resigned from Congress in November 2007 after spending 21 years in the House. He resigned the speakership after Republicans lost control of the House in the 2006 election.
Hastert will be the second ex-congressman to join Dickstein Shapiro recently. Rep. Albert Wynn, D-Md., also will start at the law and lobbying firm in June, following his primary loss to Donna Edwards earlier this year.