Goals from Steve Spriggs and Ross Watson in either half saw The Walks outfit consolidate a play-off position by extending their unbeaten league run to five matches.
Top goalscorer Spriggs bagged a first-half penalty � his seventh goal from the spot this season � before Watson wrapped up the points following a nervy performance from Lynn 19 minutes from time.
Linnets boss Gary Setchell said: "It wasn't a classic performance today but we dug in and got there.
"It's another clean sheet, another three points and a step closer to where we want to be, which is the play-offs."
On his side's sixth clean sheet of the campaign, Setchell said: "Jason Lee and Gullers (Phil Gulliver) have formed a little partnership now, as Ryan (Fryatt) and Gullers did earlier in the season, and they are looking very comfortable as a left/right combination as centre halves.
"They are not blessed, with pace but Steve Bruce and Gary Pallister (former Manchester United defenders) were never blessed with pace and they got away with it."
Team wise, Danny Beaumont came in for Jamie Thurlbourne, who left Lynn on Wednesday, and Russell Dunkley replaced George Thomson who was on the bench.
Dunkley set up strike partner Shane Tolley for the first chance of the game after four minutes, but his effort was comfortably dealt with by Alessandro Barcherini.
An indirect free-kick, following a back pass by Ross Watson, handed Rainworth a lifeline eight yards out after five minutes, but Ryan Goward blasted the set-piece into the body of Dan Quigley.
Tolley was beaten to the ball by Sam Purcicoe a few yards out following an inviting cross from Spriggs as Lynn looked to turn the screw.
Rainworth's Connor Higginson blazed over for the Wrens, who only named three substitutes on the bench for the game.
The deadlock was finally broken by Spriggs, from the penalty spot, in the 30th minute after Tolley robbed Ashley Kitchen of the ball before being brought down in the box by Goward.
Rainworth almost levelled matters three minutes later when Higginson's shot whistled past Danny Gay's post.
On the stroke of half-time, Beaumont volleyed over when well-placed in the box.
After a scrappy start to the second period, the first shot in anger came from Goward, whose free-kick flew over the woodwork.
Quigley's blockbuster was palmed away by the goalkeeper at the other end, but there was a lack of real excitement at either end of the pitch.
Twenty minutes from time a drab encounter was finally settled when George Thomson's cross was headed goalwards by Phil Gulliver and Watson pounced to hook the ball home.
Debutant Charlie Butt, who came on for the final 25 minutes, almost made it 3-0 but the youngster's shot flashed across the face of goal.
Blair Anderson and Higginson almost grabbed a consolation for Rainworth but their efforts were saved by Gay.
Former Linnet Mark Camm was an unused substitute for the Wrens after picking up a hamstring injury in midweek.
Lynn: Gay, Watson, Gulliver, Lee, Yong, Spriggs (Butt 65), Bunting, Quigley, Beaumont (Thomson 60), Tolley, Dunkley (Biles 85). Subs not used: Fryatt, White. Goal: Spriggs (pen 30), Watson (71).
Rainworth: Barcherini, Hanson, Goward, Purcicoe, Kitchen, Williams, Lloyd (Anderson 50), Hollis, Higginson, Holmes, Kimberley (Jenkins 72). Sub not used: Camm.
Referee: D. Stobbart. Attendance: 658. MoM: Jason Lee.
Report by permission of the Lynn News