[10] With regular left backs Andrew Taylor and Emanuel Pogatetz injured, Grounds made his first-team debut on 12 January 2008 in a 1–1 Premier League draw at home to Liverpool.

[15] Covering for Justin Hoyte in an unfamiliar right-back role,[17] his "last-ditch block" prevented a first-half goal, but in the second half he was fortunate that Florent Malouda failed to capitalise on his error, and he was substituted after 54 minutes with his team 3–0 down.

[22][23] The Evening Gazette suggested that "battling full-backs Tony McMahon and Jonathan Grounds, who both have some experience at this level and appear to have a more physical approach have been picked ahead of the more silky but at times suspect duo of Justin Hoyte and Andrew Taylor.

"[24] He dropped to the bench before the last match in September,[25] and played infrequently until late January, when an injury crisis caused Southgate's successor, Gordon Strachan, to bring him back into central defence.

[36] Under new manager Tony Mowbray, Grounds played six matches for Middlesbrough after his return, including a 4–3 defeat at home to Swansea City in which he scored a headed goal;[37] he partnered the equally inexperienced Seb Hines in central defence.

[51] He made a mixed start to his Oldham career: he scored the winner against Manchester City in a pre-season friendly,[52] but in the opening league fixture, Milton Keynes Dons' Daniel Powell "terrorised" him.

[56] He was ever-present through Oldham's 2012–13 FA Cup run, in which they eliminated Nottingham Forest and Liverpool,[57] drew with Everton in the fifth round through Matt Smith's stoppage-time header from Grounds's corner,[58] before losing 3–1 in the replay.

[68] He made his debut in the starting eleven for the opening-day defeat at Middlesbrough, and settled into the side as regular first choice at left back,[69] both under Clark and, after his dismissal in November, under his successor, Gary Rowett.

[70] With Birmingham 2–0 down against West Bromwich Albion in the FA Cup, Grounds steered Lloyd Dyer's low centre past the goalkeeper in first-half stoppage time for his first goal for the club; the game finished as a 2–1 defeat.

[75] According to the Birmingham Mail's Brian Dick, writing in his end-of-season review, Grounds "improved as the season developed", becoming "an increasingly confident and assured" member of the back four, "very effective in the air, pretty solid in defence but limited going forward".

[80] The Birmingham Mail thought he needed to be more assertive when dealing with crosses, and the player himself, while admitting he had had "a few shaky games", felt more settled than he had in the past and was enjoying playing regularly.

[81] Going into the 2016–17 campaign, Rowett was actively seeking to bring in another left back as competition:[82] when Rhoys Wiggins arrived on loan from AFC Bournemouth, BBC WM's Richard Wilford wrote that he became "the first serious challenger to Jonathan Grounds at left-back in two years.

"[83] Grounds retained his place for some weeks as the team went seven matches unbeaten[57] and provided the assist for Che Adams's equalising goal away to Preston North End,[84] but a fifth booking of the season in a defeat at Burton Albion earned him a one-match suspension and gave Wiggins his opportunity.

He started the local derby against Aston Villa, produced what Rowett dubbed an "absolutely brilliant" performance until in stoppage time, he suffered a knee injury that ended his season.

[91] Birmingham took up their option to extend Grounds's contract for another year,[92] and he continued in the first team until the close of the transfer window, when the defence was reshuffled to accommodate Emilio Nsue and new arrival Maxime Colin.

[97] Monk decided that Grounds was one of several senior players who did not form part of his plans for the 2018–19 season in light of the club's issues with the EFL's profitability and sustainability rules.

[103] He came into the first team rather sooner than anticipated after Andy Taylor suffered a calf injury, and had six weeks in the starting eleven despite what manager Phil Parkinson and his staff admitted was insufficient preparation and lack of match fitness.

He made his first appearance for three months in Bolton's final match of the season, in which Parkinson struggled to raise a team as several players had cancelled their contracts because they had not been paid and others were unwilling to risk injury that might jeopardise a move elsewhere.

[111] He made his debut on 26 September, as a late substitute in a 4–2 league win at home to Burton Albion,[112] and injuries at centre-back meant that despite his lack of match fitness, he soon found himself in the starting eleven.

[120] He made his debut in the starting eleven for the opening fixture of the season, a goalless draw at home to Bradford City,[121] and was sent off for receiving a second yellow card towards the end of the next league game, a 3–0 defeat away to Leyton Orient.