diff --git a/subsys/bluetooth/controller/ll_sw/lll_conn_iso.h b/subsys/bluetooth/controller/ll_sw/lll_conn_iso.h
index 31e2f70fcd6..676c574155e 100644
--- a/subsys/bluetooth/controller/ll_sw/lll_conn_iso.h
+++ b/subsys/bluetooth/controller/ll_sw/lll_conn_iso.h
@@ -45,7 +45,8 @@ struct lll_conn_iso_stream {
 	struct lll_conn_iso_stream_rxtx tx; /* TX parameters */
 
 	/* Event and payload counters */
-	uint64_t event_count:39;    /* cisEventCount */
+	uint64_t event_count_prepare:39; /* cisEventCount in overlapping CIG prepare */
+	uint64_t event_count:39;         /* cisEventCount in current CIG event */
 
 	/* Acknowledgment and flow control */
 	uint8_t sn:1;               /* Sequence number */
diff --git a/subsys/bluetooth/controller/ll_sw/nordic/lll/lll_central_iso.c b/subsys/bluetooth/controller/ll_sw/nordic/lll/lll_central_iso.c
index 065b058f8fd..526403e92d9 100644
--- a/subsys/bluetooth/controller/ll_sw/nordic/lll/lll_central_iso.c
+++ b/subsys/bluetooth/controller/ll_sw/nordic/lll/lll_central_iso.c
@@ -150,6 +150,9 @@ static int prepare_cb(struct lll_prepare_param *p)
 	/* Get reference to ACL context */
 	conn_lll = ull_conn_lll_get(cis_lll->acl_handle);
 
+	/* Pick the event_count calculated in the ULL prepare */
+	cis_lll->event_count = cis_lll->event_count_prepare;
+
 	/* Event counter value,  0-15 bit of cisEventCounter */
 	event_counter = cis_lll->event_count;
 
@@ -357,6 +360,9 @@ static int prepare_cb(struct lll_prepare_param *p)
 	do {
 		cis_lll = ull_conn_iso_lll_stream_get_by_group(cig_lll, &cis_handle);
 		if (cis_lll && cis_lll->active) {
+			/* Pick the event_count calculated in the ULL prepare */
+			cis_lll->event_count = cis_lll->event_count_prepare;
+
 			/* Adjust sn and nesn for skipped CIG events */
 			payload_count_lazy_update(cis_lll, cig_lll->latency_event);
 
diff --git a/subsys/bluetooth/controller/ll_sw/nordic/lll/lll_peripheral_iso.c b/subsys/bluetooth/controller/ll_sw/nordic/lll/lll_peripheral_iso.c
index 3ff20706dc6..00e641fd151 100644
--- a/subsys/bluetooth/controller/ll_sw/nordic/lll/lll_peripheral_iso.c
+++ b/subsys/bluetooth/controller/ll_sw/nordic/lll/lll_peripheral_iso.c
@@ -164,6 +164,9 @@ static int prepare_cb(struct lll_prepare_param *p)
 	/* Get reference to ACL context */
 	conn_lll = ull_conn_lll_get(cis_lll->acl_handle);
 
+	/* Pick the event_count calculated in the ULL prepare */
+	cis_lll->event_count = cis_lll->event_count_prepare;
+
 	/* Event counter value,  0-15 bit of cisEventCounter */
 	event_counter = cis_lll->event_count;
 
@@ -374,6 +377,9 @@ static int prepare_cb(struct lll_prepare_param *p)
 			break;
 		}
 
+		/* Pick the event_count calculated in the ULL prepare */
+		cis_lll->event_count = cis_lll->event_count_prepare;
+
 		/* Adjust sn and nesn for skipped CIG events */
 		payload_count_lazy(cis_lll, cig_lll->latency_event);
 
diff --git a/subsys/bluetooth/controller/ll_sw/ull_central_iso.c b/subsys/bluetooth/controller/ll_sw/ull_central_iso.c
index fa3e3715664..d49256e3b09 100644
--- a/subsys/bluetooth/controller/ll_sw/ull_central_iso.c
+++ b/subsys/bluetooth/controller/ll_sw/ull_central_iso.c
@@ -929,6 +929,11 @@ uint8_t ull_central_iso_setup(uint16_t cis_handle,
 #if defined(CONFIG_BT_CTLR_ISOAL_PSN_IGNORE)
 	cis->pkt_seq_num = 0U;
 #endif /* CONFIG_BT_CTLR_ISOAL_PSN_IGNORE */
+	/* It is intentional to initialize to the 39 bit maximum value and rollover to 0 in the
+	 * prepare function, the event counter is pre-incremented in prepare function for the
+	 * current ISO event.
+	 */
+	cis->lll.event_count_prepare = LLL_CONN_ISO_EVENT_COUNT_MAX;
 	cis->lll.event_count = LLL_CONN_ISO_EVENT_COUNT_MAX;
 	cis->lll.next_subevent = 0U;
 	cis->lll.tifs_us = conn->lll.tifs_cis_us;
diff --git a/subsys/bluetooth/controller/ll_sw/ull_conn_iso.c b/subsys/bluetooth/controller/ll_sw/ull_conn_iso.c
index a55d023668f..b25267a34bd 100644
--- a/subsys/bluetooth/controller/ll_sw/ull_conn_iso.c
+++ b/subsys/bluetooth/controller/ll_sw/ull_conn_iso.c
@@ -711,17 +711,17 @@ void ull_conn_iso_ticker_cb(uint32_t ticks_at_expire, uint32_t ticks_drift,
 		 * has been reached, and offset calculated.
 		 */
 		if (cis->lll.handle != 0xFFFF && cis->lll.active) {
-			cis->lll.event_count += (lazy + 1U);
+			cis->lll.event_count_prepare += (lazy + 1U);
 
 #if !defined(CONFIG_BT_CTLR_JIT_SCHEDULING)
-			cis->lll.event_count -= cis->lll.lazy_active;
+			cis->lll.event_count_prepare -= cis->lll.lazy_active;
 			cis->lll.lazy_active = 0U;
 #endif /* !CONFIG_BT_CTLR_JIT_SCHEDULING */
 
 			leading_event_count = MAX(leading_event_count,
-						cis->lll.event_count);
+						cis->lll.event_count_prepare);
 
-			ull_iso_lll_event_prepare(cis->lll.handle, cis->lll.event_count);
+			ull_iso_lll_event_prepare(cis->lll.handle, cis->lll.event_count_prepare);
 		}
 
 		/* Latch datapath validity entering event */
@@ -975,7 +975,7 @@ void ull_conn_iso_start(struct ll_conn *conn, uint16_t cis_handle,
 				cis_offset = cis->offset + iso_interval_us - acl_latency_us;
 			}
 
-			cis->lll.event_count += lost_cig_events;
+			cis->lll.event_count_prepare += lost_cig_events;
 
 			lost_payloads = (lost_cig_events - (cis->lll.rx.ft - 1)) * cis->lll.rx.bn;
 			cis->lll.rx.payload_count += lost_payloads;
@@ -1520,7 +1520,7 @@ void ull_conn_iso_transmit_test_cig_interval(uint16_t handle, uint32_t ticks_at_
 		 * on 64-bit sdu_counter:
 		 *   (39 bits x 22 bits (4x10^6 us) = 61 bits / 8 bits (255 us) = 53 bits)
 		 */
-		sdu_counter = DIV_ROUND_UP((cis->lll.event_count + 1U) * iso_interval,
+		sdu_counter = DIV_ROUND_UP((cis->lll.event_count_prepare + 1U) * iso_interval,
 					       sdu_interval);
 
 		if (cis->hdr.test_mode.tx.sdu_counter == 0U) {
diff --git a/subsys/bluetooth/controller/ll_sw/ull_peripheral_iso.c b/subsys/bluetooth/controller/ll_sw/ull_peripheral_iso.c
index 345fddb8746..77b3f240f1b 100644
--- a/subsys/bluetooth/controller/ll_sw/ull_peripheral_iso.c
+++ b/subsys/bluetooth/controller/ll_sw/ull_peripheral_iso.c
@@ -333,6 +333,11 @@ uint8_t ull_peripheral_iso_setup(struct pdu_data_llctrl_cis_ind *ind,
 #if defined(CONFIG_BT_CTLR_ISOAL_PSN_IGNORE)
 	cis->pkt_seq_num = 0U;
 #endif /* CONFIG_BT_CTLR_ISOAL_PSN_IGNORE */
+	/* It is intentional to initialize to the 39 bit maximum value and rollover to 0 in the
+	 * prepare function, the event counter is pre-incremented in prepare function for the
+	 * current ISO event.
+	 */
+	cis->lll.event_count_prepare = LLL_CONN_ISO_EVENT_COUNT_MAX;
 	cis->lll.event_count = LLL_CONN_ISO_EVENT_COUNT_MAX;
 	cis->lll.next_subevent = 0U;
 	cis->lll.tifs_us = conn->lll.tifs_cis_us;