With Marek Stech having broken a finger in the 1-0 loss to Birmingham on Saturday, Johnson moved quickly to add Wales international Hennessey, a goalkeeper he knew from his Bristol City days, to his squad.
And with the player needing regular football after a long spell on the sidelines, the Yeovil boss believes his Championship move is a great one for all parties.
"It suits everybody," he told BBC Somerset. "Wolves need him to play first team football games, we need a first team keeper, and it's just a perfect situation. It's perfect timing.
"I know Wayne well, as I loaned him at Bristol City when he was a young lad. He didn't manage to get a game because he put his shoulder out in training. But I've kept in touch and watched him for a long time, and he's now a top goalkeeper.
"He's not in the first team at the moment as he had an injury last year. So it suits everybody. The player wants to play first team football."
Hennessey could come up against his new team-mate Paddy Madden on Wednesday night with the Irish striker in the squad to face Wales in Cardiff.