Mitch McConnell comes in peace ... he was all smiles as he arrived home after a hard day's work on Capitol Hill ... and video shows the Senator in great spirits.

After three hours of work in the Senate, the Kentucky lawmaker returned to his D.C. home Tuesday evening ... and he flashed a peace sign as he was wheeled inside.

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Mitch was in a wheelchair ... with four people helping him.

The sighting came after Mitch voted for a cloture motion to end the debate on a district judge's nomination ... but it fell short of the 60 votes needed.

Mitch resurfaced last week after disappearing from public view for three months following a bad fall in June, which required a hospital stay and a rehab stint.

He says his recovery "has been a long and often frustrating process, and the lingering effects of childhood polio haven't made it any easier."