The former environment minister said he was overwhelmed by his 7,329 votes in the constituency, more than 2,000 ballots over the quota.
Mr Poots said he expects all three of his running mates - Jonathan Craig, Paul Givan and Brenda Hale - to be returned to Stormont along with him.
"Lagan Valley will play an integral part in the DUP remaining the biggest party at Stormont," he said.
Mr Poots insisted it wasn't important for him to outpoll the Ulster Unionist Party's Basil McCrea, who was also elected on the first count, on 5,771 votes.
The DUP MLA said the key issue now was a "coalition" with the Ulster Unionist Party (UUP) and the Traditional Unionist Voice (TUV) ahead of the next polls.
A united front was needed to secure the union and maintain the British tradition in Northern Ireland, he said.
"I would suggest to members of the Ulster Unionist Party (UUP) that they reflect over the next weeks and months about looking to do business with the DUP," he added.
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