Shares of Teco, which operates in Florida and New Mexico, rose to $26.70 in extended trading on Friday, below the offer price of $27.55 per share in cash.
The deal is valued at $10.4 billion including the assumption of about $3.9 billion in debt, the companies said in a statement.
Teco had 233.6 million shares outstanding as of June 30.
Emera's total assets are expected to increase to about $20 billion from $9.89 billion after the deal, and will see it serve more than 2.4 million electric and gas customers.
A majority of those assets will be based in Florida, where Teco operates its Tampa Electric and Peoples Gas System utilities.
Currently, Emera has investments in northeastern North America and in four Caribbean countries.
Utilities regulators for the District of Columbia last week denied Exelon Corp's (EXC.N) $6.8 billion bid for Pepco Holdings Inc POM.N, dealing a major blow to a deal that would have created the top power distributor in the United States.
The Teco deal is expected to add to Emera's earnings in the first year after it closes.
Teco said in July that it was "exploring strategic alternatives."
J.P. Morgan was Emera's lead adviser and Davis Polk & Wardwell LLP and Osler, Hoskin & Harcourt LLP were its legal advisers.
Morgan Stanley was Teco's lead strategic adviser and Skadden Arps, Slate, Meagher & Flom LLP and Holland & Knight LLP were its legal advisers.
Reporting by Yashaswini Swamynathan and Narottam Medhora in Bengaluru; Editing by Kirti Pandey and Maju Samuel