Tranmere had earlier reached the summit with a 1-0 victory at Wrexham, but Lincoln matched their promotion rivals' result to reclaim first place.
The home side had a golden opportunity to open the scoring in the first half when Lee Angol was fouled in the area, but  Alan Power's penalty was brilliantly saved by Ross Flitney.
Bromley continued to frustrate Lincoln until Knott came off the bench to drill in a shot with his first touch of the ball on 65 minutes to earn his side three crucial points.
Match report supplied by the Press Association
Match ends, Lincoln City 1, Bromley 0.
Second Half ends, Lincoln City 1, Bromley 0.
Sean Raggett (Lincoln City) is shown the yellow card for a bad foul.
Substitution, Lincoln City. Elliot Whitehouse replaces Matt Rhead.
Alan Dunne (Bromley) is shown the yellow card for a bad foul.
Substitution, Bromley. Bradley Goldberg replaces Blair Turgott.
Substitution, Bromley. Louis Dennis replaces Shane McLoughlin.
Goal!  Lincoln City 1, Bromley 0. Billy Knott (Lincoln City).
Substitution, Lincoln City. Josh Ginnelly replaces Harry Anderson.
Substitution, Lincoln City. Billy Knott replaces Alan Power.
Lee Angol (Lincoln City) is shown the yellow card for a bad foul.
Blair Turgott (Bromley) is shown the yellow card for a bad foul.
Second Half begins Lincoln City 0, Bromley 0.
First Half ends, Lincoln City 0, Bromley 0.
Luke Waterfall (Lincoln City) is shown the yellow card for a bad foul.
Substitution, Bromley. Daniel Johnson replaces Ben Chorley.
First Half begins.
Lineups are announced and players are warming up.
Substitute Billy Knott scored his first goal for Lincoln to fire the Imps back to the top of the National League.