The final price could rise to up to $70 million if certain benchmarks are achieved.
The company did not acquire Emeril's Homebase, which includes Lagasse's 11 restaurants and corporate office.
Martha Stewart Living said the deal will "contribute immediately to our performance," adding $8 million in earnings before interest, taxes, depreciation and amortization. The acquired assets generated $14 million in revenue in 2007.
Martha Stewart Living expects the deal to close in the second quarter.
Lagasse joined the Food Network in 1993 and has hosted over 1,600 shows. His programs "The Essence of Emeril" and "Emeril Live" reach more than 85 million homes daily.