Scarborough raced to a 14-0 lead in the early stages of a close-fought Yorkshire One clash at Silver Royd, skipper Matty Jones and fly-half Tom Harrison grabbing a try apiece in the opening 15 minutes of the game, Harrison converting both.
Keighley got themselves back into the game in an evenly-contested second quarter and reduced the arrears to seven points with a close-range try by Hooker Shaun Minikin, converted by off-half Alex Brown on the half-hour and trailed 14-7 at the break.
The visitors took control after the break but a combination of good home defence and an outbreak of white-line fever saw them fail to capitalise on their territorial and physical possession.
Scarborough stretched their lead to 19-7 on the hour on a rare incursion into Keighley territory when prop Nino Cutino powered over from a catch and drive.
In an exciting last 10 minutes Harrison stretched the lead to 22-7 with a penalty before a try from number eight Lee Sugden gave Keighley hope.
However a late flourish from Scarborough saw slick work down their left flank release centre Tom Ratcliffe to sell a cute dummy and glide over to seal a bonus point victory at 27-15.