Steve Lomas has come to an agreement to become the new manager of Championship club Millwall.
Millwall chairman John Berylson said: "I was tremendously impressed with Steve. He has great passion and energy, knows a lot about Millwall as a club already, and this is a job he is genuinely hungry for.
"In some respects, following Kenny Jackett is a tall order, but Steve is very different from his predecessor, younger and with a fresh approach.
"I believe our fans will take to him, and to those who say we shouldn't have appointed a former captain of our biggest rivals, my response is, he has the desire to become a great Millwall manager.
"He understands the rivalry and is keen to be judged over time on his commitment to our club and what he can help us achieve.
"From our point of view, we want the best man for the job, and we believe that man is Steve Lomas.
"I would like to thank the chairman of St Johnstone for allowing us to appoint Steve and for the courteous and professional way in which our business has been conducted."