Celtic boss Lennon guided the Hoops to a second consecutive Scottish Premier League title, while McCall's Motherwell currently sit in second spot.
Butcher could secure European football for Inverness if they can retain third place, while Johnston led Queen of the South to an emphatic Irn-Bru Second Division title success, as well as the Challenge Cup.
Managers from across the four Scottish leagues, as well as national team boss Gordon Strachan, voted for the manager they think has had the best season.
The winner will be announced at Glasgow's Hilton Hotel on May 5.
PFA Scotland chief executive Fraser Wishart said: "Having counted the votes, these are the top four as far as the current managers across the SPL and SFL are concerned.
"Each manager was asked to vote for the best across all divisions. This was the closest-run contest we have ever had.
"It speaks volumes about the quality of managers we have in our game in Scotland and in fact, there are a few more managers who I am sure could also lay claim to the title.
"All four nominees have had outstanding seasons and thoroughly deserve the accolade of being voted the best by their peers."